Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics1

page 1

Powering Advanced Microprocessors

2005年4月21日

鄒 應 嶼 教 授

國立交通大學 電機與控制工程研究所

國立交通大學電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab NCTU Taiwan

httppowerlabcnnctuedutw

POWERLABNCTU

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

台灣新竹交通大學 bull 電機與控制工程研究所

Filename PEMC-03投影片A02 投影片電力電子系統晶片 (研究所)SoC-07Powering Microprocessorsppt

page 2

Contents

1 Development of Microprocessors2 Power Supply for mP amp Portable IA3 Microprocessor Power-Supply Specifications4 Power Supply Specifications for Microprocessors5 Effect of Device and PCB Parasitics6 Converter Topologies7 Efficiency Optimization by Loss Reduction8 Control Techniques9 Achieving Fast Load Transient Response10 Optimally Compensated Active Voltage Positioning11 Input Current didt Reduction12 Component and Protection Issues13 Design Examples14 Math CAD Design Spreadsheet

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics2

page 3

Development of Microprocessors

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 4

Development of Microprocessors

Development of MicroprocessorsDynamic Power Dissipation in CMOS VLSIPower Dissipation Inside CPUPower Supply Voltage for Advanced MicroprocessorsPower Conversion and Control Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics3

page 5

Development of Microprocessors

0

100

200

300

400

500

70 75 80 85 90 95 20

MHz

Year0

1

2

3

4

5

6

7

70 75 80 85 90 95 20

Million Transistors

Year

Clock Frequency No of Transistors

page 6

Dynamic Power Dissipation in CMOS VLSI

5 factors of dynamic power dissipation and low power design strategies

Supply voltage (voltage scaling)Switching activity (scheduling)Total no of transistors (circuit minimization)Operating frequency (IC layout process innovation)Physical capacitance (process innovation)

These parameters are not completely orthogonal and cannot be optimized independently

NfCV21αP c

2ddD sdotsdotsdot=

VDD

C

a a

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics4

page 7

Power Dissipation Inside CPU

Dynamic Power Losses

Short Circuit Losses

Static Current Losses

Junction Losses

NfCVP cddD sdotsdotsdot= 2

21α

α activity scale (00 ~ 10)c gate output capacitancefc clock frequencyN number of transistors

A hotspot is an area of a processor which runs lsquohotterrsquo than other areas

page 8

Power Consumption in Advanced Microprocessors

0

1

2

3

4

5

84 86 88 90 94 96 98 20

Volts

Year

NfCVP cddD sdotsdotsdot= 2

21α

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics5

page 9

Increasing Complexity hellip

Moorersquos Law

lsquo75 lsquo80 lsquo85 lsquo90 lsquo95 lsquo00 lsquo05 lsquo10 lsquo151

10

100

1000

10000

100000

1000000k

Source Intel

1 BillionTransistors

808680286

i386TM Processori486TM Processor

Pentiumreg Pro ProcessorPentiumreg III Processor

Pentiumreg 4 ProcessorPentiumreg II Processor

Pentiumreg Processor

Number of Transistors Per Chip Will Double Every 18 Months

page 10

MooresrsquoLaw on Gate Width

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics6

page 11

Increasing Power Requirement

Ref Intel and 2001 International Technology Roadmap for Semiconductors (ITRS)

Intel processors fall within the TRS power road map window100 W+ processors in 2006

200

175

150

125

100

75

50

25

01998 2000 2002 2004 2006 2008 2010 2012 2014

Pow

er (W

)

ItaniumTM ProcessorITRS High Performance CPU

x xx

x x x x xx

x

x

ItaniumTM 2 ProcessorITRS Cost-Performance CPU

Itaniumreg 4 Processor

Itaniumreg II Processor

Itaniumreg III Processor

page 12

High Currents Low Voltages hellip

Voltage scaling ~ 1V by 2006Current scaling to 100-175 A ~ 2006-2009Power delivery system impedance dropping below 1 mΩ ~ 2008

2000 2002 2004 2006 2008 2010 2012 2014

250

200

150

100

50

0

300

125

1

075

05

025

0

15

Icc

(A)

Year

Vcc

(A)

x xx x

x x

x

x

IccHigh-Performance CPU

Icc Cost-Performance CPU

Vcc

Currents Calculated form ITRS 2001

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics7

page 13

Power Conversion and Control Technology

Time High dVdt and dIdt (Faster Switching)

Voltage Lower voltage top reduce power losses

Power Higher power for distributed computing

page 14

CPU Power Losses Reduction Schemes

winding resistancecopper 06 Ohmsmil ftaluminum 1701 Ohmsmil ft

Power Losses Reduction SchemesVoltage ScalingSOI Silicon-On-InsulatorCopper Interconnect Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics8

page 15

Technology Challenge

Market Driving ForceMake it more intelligent (Easy to Use)

Make it operate faster

Make it smaller

Make it more efficient

Make it cheaper (Can be Use)

High-Speed is Essential

Powering High-Speed mP amp DSP

page 16

Component Solution Component Size Reduction

SMT Component

Size

080506030402

0201

12mm3mm

NACxx SERIES SMT ALUMINUM ELECTROLYTIC CAPACITORS

NRC SERIES CHIP RESISTORS

NMC SERIESCERAMIC

CHIP CAPACITORS

0201 bull

0201

bull

NINNIS SERIES CHIP INDUCTORS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics2

page 3

Development of Microprocessors

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 4

Development of Microprocessors

Development of MicroprocessorsDynamic Power Dissipation in CMOS VLSIPower Dissipation Inside CPUPower Supply Voltage for Advanced MicroprocessorsPower Conversion and Control Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics3

page 5

Development of Microprocessors

0

100

200

300

400

500

70 75 80 85 90 95 20

MHz

Year0

1

2

3

4

5

6

7

70 75 80 85 90 95 20

Million Transistors

Year

Clock Frequency No of Transistors

page 6

Dynamic Power Dissipation in CMOS VLSI

5 factors of dynamic power dissipation and low power design strategies

Supply voltage (voltage scaling)Switching activity (scheduling)Total no of transistors (circuit minimization)Operating frequency (IC layout process innovation)Physical capacitance (process innovation)

These parameters are not completely orthogonal and cannot be optimized independently

NfCV21αP c

2ddD sdotsdotsdot=

VDD

C

a a

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics4

page 7

Power Dissipation Inside CPU

Dynamic Power Losses

Short Circuit Losses

Static Current Losses

Junction Losses

NfCVP cddD sdotsdotsdot= 2

21α

α activity scale (00 ~ 10)c gate output capacitancefc clock frequencyN number of transistors

A hotspot is an area of a processor which runs lsquohotterrsquo than other areas

page 8

Power Consumption in Advanced Microprocessors

0

1

2

3

4

5

84 86 88 90 94 96 98 20

Volts

Year

NfCVP cddD sdotsdotsdot= 2

21α

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics5

page 9

Increasing Complexity hellip

Moorersquos Law

lsquo75 lsquo80 lsquo85 lsquo90 lsquo95 lsquo00 lsquo05 lsquo10 lsquo151

10

100

1000

10000

100000

1000000k

Source Intel

1 BillionTransistors

808680286

i386TM Processori486TM Processor

Pentiumreg Pro ProcessorPentiumreg III Processor

Pentiumreg 4 ProcessorPentiumreg II Processor

Pentiumreg Processor

Number of Transistors Per Chip Will Double Every 18 Months

page 10

MooresrsquoLaw on Gate Width

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics6

page 11

Increasing Power Requirement

Ref Intel and 2001 International Technology Roadmap for Semiconductors (ITRS)

Intel processors fall within the TRS power road map window100 W+ processors in 2006

200

175

150

125

100

75

50

25

01998 2000 2002 2004 2006 2008 2010 2012 2014

Pow

er (W

)

ItaniumTM ProcessorITRS High Performance CPU

x xx

x x x x xx

x

x

ItaniumTM 2 ProcessorITRS Cost-Performance CPU

Itaniumreg 4 Processor

Itaniumreg II Processor

Itaniumreg III Processor

page 12

High Currents Low Voltages hellip

Voltage scaling ~ 1V by 2006Current scaling to 100-175 A ~ 2006-2009Power delivery system impedance dropping below 1 mΩ ~ 2008

2000 2002 2004 2006 2008 2010 2012 2014

250

200

150

100

50

0

300

125

1

075

05

025

0

15

Icc

(A)

Year

Vcc

(A)

x xx x

x x

x

x

IccHigh-Performance CPU

Icc Cost-Performance CPU

Vcc

Currents Calculated form ITRS 2001

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics7

page 13

Power Conversion and Control Technology

Time High dVdt and dIdt (Faster Switching)

Voltage Lower voltage top reduce power losses

Power Higher power for distributed computing

page 14

CPU Power Losses Reduction Schemes

winding resistancecopper 06 Ohmsmil ftaluminum 1701 Ohmsmil ft

Power Losses Reduction SchemesVoltage ScalingSOI Silicon-On-InsulatorCopper Interconnect Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics8

page 15

Technology Challenge

Market Driving ForceMake it more intelligent (Easy to Use)

Make it operate faster

Make it smaller

Make it more efficient

Make it cheaper (Can be Use)

High-Speed is Essential

Powering High-Speed mP amp DSP

page 16

Component Solution Component Size Reduction

SMT Component

Size

080506030402

0201

12mm3mm

NACxx SERIES SMT ALUMINUM ELECTROLYTIC CAPACITORS

NRC SERIES CHIP RESISTORS

NMC SERIESCERAMIC

CHIP CAPACITORS

0201 bull

0201

bull

NINNIS SERIES CHIP INDUCTORS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics3

page 5

Development of Microprocessors

0

100

200

300

400

500

70 75 80 85 90 95 20

MHz

Year0

1

2

3

4

5

6

7

70 75 80 85 90 95 20

Million Transistors

Year

Clock Frequency No of Transistors

page 6

Dynamic Power Dissipation in CMOS VLSI

5 factors of dynamic power dissipation and low power design strategies

Supply voltage (voltage scaling)Switching activity (scheduling)Total no of transistors (circuit minimization)Operating frequency (IC layout process innovation)Physical capacitance (process innovation)

These parameters are not completely orthogonal and cannot be optimized independently

NfCV21αP c

2ddD sdotsdotsdot=

VDD

C

a a

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics4

page 7

Power Dissipation Inside CPU

Dynamic Power Losses

Short Circuit Losses

Static Current Losses

Junction Losses

NfCVP cddD sdotsdotsdot= 2

21α

α activity scale (00 ~ 10)c gate output capacitancefc clock frequencyN number of transistors

A hotspot is an area of a processor which runs lsquohotterrsquo than other areas

page 8

Power Consumption in Advanced Microprocessors

0

1

2

3

4

5

84 86 88 90 94 96 98 20

Volts

Year

NfCVP cddD sdotsdotsdot= 2

21α

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics5

page 9

Increasing Complexity hellip

Moorersquos Law

lsquo75 lsquo80 lsquo85 lsquo90 lsquo95 lsquo00 lsquo05 lsquo10 lsquo151

10

100

1000

10000

100000

1000000k

Source Intel

1 BillionTransistors

808680286

i386TM Processori486TM Processor

Pentiumreg Pro ProcessorPentiumreg III Processor

Pentiumreg 4 ProcessorPentiumreg II Processor

Pentiumreg Processor

Number of Transistors Per Chip Will Double Every 18 Months

page 10

MooresrsquoLaw on Gate Width

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics6

page 11

Increasing Power Requirement

Ref Intel and 2001 International Technology Roadmap for Semiconductors (ITRS)

Intel processors fall within the TRS power road map window100 W+ processors in 2006

200

175

150

125

100

75

50

25

01998 2000 2002 2004 2006 2008 2010 2012 2014

Pow

er (W

)

ItaniumTM ProcessorITRS High Performance CPU

x xx

x x x x xx

x

x

ItaniumTM 2 ProcessorITRS Cost-Performance CPU

Itaniumreg 4 Processor

Itaniumreg II Processor

Itaniumreg III Processor

page 12

High Currents Low Voltages hellip

Voltage scaling ~ 1V by 2006Current scaling to 100-175 A ~ 2006-2009Power delivery system impedance dropping below 1 mΩ ~ 2008

2000 2002 2004 2006 2008 2010 2012 2014

250

200

150

100

50

0

300

125

1

075

05

025

0

15

Icc

(A)

Year

Vcc

(A)

x xx x

x x

x

x

IccHigh-Performance CPU

Icc Cost-Performance CPU

Vcc

Currents Calculated form ITRS 2001

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics7

page 13

Power Conversion and Control Technology

Time High dVdt and dIdt (Faster Switching)

Voltage Lower voltage top reduce power losses

Power Higher power for distributed computing

page 14

CPU Power Losses Reduction Schemes

winding resistancecopper 06 Ohmsmil ftaluminum 1701 Ohmsmil ft

Power Losses Reduction SchemesVoltage ScalingSOI Silicon-On-InsulatorCopper Interconnect Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics8

page 15

Technology Challenge

Market Driving ForceMake it more intelligent (Easy to Use)

Make it operate faster

Make it smaller

Make it more efficient

Make it cheaper (Can be Use)

High-Speed is Essential

Powering High-Speed mP amp DSP

page 16

Component Solution Component Size Reduction

SMT Component

Size

080506030402

0201

12mm3mm

NACxx SERIES SMT ALUMINUM ELECTROLYTIC CAPACITORS

NRC SERIES CHIP RESISTORS

NMC SERIESCERAMIC

CHIP CAPACITORS

0201 bull

0201

bull

NINNIS SERIES CHIP INDUCTORS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics4

page 7

Power Dissipation Inside CPU

Dynamic Power Losses

Short Circuit Losses

Static Current Losses

Junction Losses

NfCVP cddD sdotsdotsdot= 2

21α

α activity scale (00 ~ 10)c gate output capacitancefc clock frequencyN number of transistors

A hotspot is an area of a processor which runs lsquohotterrsquo than other areas

page 8

Power Consumption in Advanced Microprocessors

0

1

2

3

4

5

84 86 88 90 94 96 98 20

Volts

Year

NfCVP cddD sdotsdotsdot= 2

21α

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics5

page 9

Increasing Complexity hellip

Moorersquos Law

lsquo75 lsquo80 lsquo85 lsquo90 lsquo95 lsquo00 lsquo05 lsquo10 lsquo151

10

100

1000

10000

100000

1000000k

Source Intel

1 BillionTransistors

808680286

i386TM Processori486TM Processor

Pentiumreg Pro ProcessorPentiumreg III Processor

Pentiumreg 4 ProcessorPentiumreg II Processor

Pentiumreg Processor

Number of Transistors Per Chip Will Double Every 18 Months

page 10

MooresrsquoLaw on Gate Width

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics6

page 11

Increasing Power Requirement

Ref Intel and 2001 International Technology Roadmap for Semiconductors (ITRS)

Intel processors fall within the TRS power road map window100 W+ processors in 2006

200

175

150

125

100

75

50

25

01998 2000 2002 2004 2006 2008 2010 2012 2014

Pow

er (W

)

ItaniumTM ProcessorITRS High Performance CPU

x xx

x x x x xx

x

x

ItaniumTM 2 ProcessorITRS Cost-Performance CPU

Itaniumreg 4 Processor

Itaniumreg II Processor

Itaniumreg III Processor

page 12

High Currents Low Voltages hellip

Voltage scaling ~ 1V by 2006Current scaling to 100-175 A ~ 2006-2009Power delivery system impedance dropping below 1 mΩ ~ 2008

2000 2002 2004 2006 2008 2010 2012 2014

250

200

150

100

50

0

300

125

1

075

05

025

0

15

Icc

(A)

Year

Vcc

(A)

x xx x

x x

x

x

IccHigh-Performance CPU

Icc Cost-Performance CPU

Vcc

Currents Calculated form ITRS 2001

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics7

page 13

Power Conversion and Control Technology

Time High dVdt and dIdt (Faster Switching)

Voltage Lower voltage top reduce power losses

Power Higher power for distributed computing

page 14

CPU Power Losses Reduction Schemes

winding resistancecopper 06 Ohmsmil ftaluminum 1701 Ohmsmil ft

Power Losses Reduction SchemesVoltage ScalingSOI Silicon-On-InsulatorCopper Interconnect Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics8

page 15

Technology Challenge

Market Driving ForceMake it more intelligent (Easy to Use)

Make it operate faster

Make it smaller

Make it more efficient

Make it cheaper (Can be Use)

High-Speed is Essential

Powering High-Speed mP amp DSP

page 16

Component Solution Component Size Reduction

SMT Component

Size

080506030402

0201

12mm3mm

NACxx SERIES SMT ALUMINUM ELECTROLYTIC CAPACITORS

NRC SERIES CHIP RESISTORS

NMC SERIESCERAMIC

CHIP CAPACITORS

0201 bull

0201

bull

NINNIS SERIES CHIP INDUCTORS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics5

page 9

Increasing Complexity hellip

Moorersquos Law

lsquo75 lsquo80 lsquo85 lsquo90 lsquo95 lsquo00 lsquo05 lsquo10 lsquo151

10

100

1000

10000

100000

1000000k

Source Intel

1 BillionTransistors

808680286

i386TM Processori486TM Processor

Pentiumreg Pro ProcessorPentiumreg III Processor

Pentiumreg 4 ProcessorPentiumreg II Processor

Pentiumreg Processor

Number of Transistors Per Chip Will Double Every 18 Months

page 10

MooresrsquoLaw on Gate Width

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics6

page 11

Increasing Power Requirement

Ref Intel and 2001 International Technology Roadmap for Semiconductors (ITRS)

Intel processors fall within the TRS power road map window100 W+ processors in 2006

200

175

150

125

100

75

50

25

01998 2000 2002 2004 2006 2008 2010 2012 2014

Pow

er (W

)

ItaniumTM ProcessorITRS High Performance CPU

x xx

x x x x xx

x

x

ItaniumTM 2 ProcessorITRS Cost-Performance CPU

Itaniumreg 4 Processor

Itaniumreg II Processor

Itaniumreg III Processor

page 12

High Currents Low Voltages hellip

Voltage scaling ~ 1V by 2006Current scaling to 100-175 A ~ 2006-2009Power delivery system impedance dropping below 1 mΩ ~ 2008

2000 2002 2004 2006 2008 2010 2012 2014

250

200

150

100

50

0

300

125

1

075

05

025

0

15

Icc

(A)

Year

Vcc

(A)

x xx x

x x

x

x

IccHigh-Performance CPU

Icc Cost-Performance CPU

Vcc

Currents Calculated form ITRS 2001

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics7

page 13

Power Conversion and Control Technology

Time High dVdt and dIdt (Faster Switching)

Voltage Lower voltage top reduce power losses

Power Higher power for distributed computing

page 14

CPU Power Losses Reduction Schemes

winding resistancecopper 06 Ohmsmil ftaluminum 1701 Ohmsmil ft

Power Losses Reduction SchemesVoltage ScalingSOI Silicon-On-InsulatorCopper Interconnect Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics8

page 15

Technology Challenge

Market Driving ForceMake it more intelligent (Easy to Use)

Make it operate faster

Make it smaller

Make it more efficient

Make it cheaper (Can be Use)

High-Speed is Essential

Powering High-Speed mP amp DSP

page 16

Component Solution Component Size Reduction

SMT Component

Size

080506030402

0201

12mm3mm

NACxx SERIES SMT ALUMINUM ELECTROLYTIC CAPACITORS

NRC SERIES CHIP RESISTORS

NMC SERIESCERAMIC

CHIP CAPACITORS

0201 bull

0201

bull

NINNIS SERIES CHIP INDUCTORS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics6

page 11

Increasing Power Requirement

Ref Intel and 2001 International Technology Roadmap for Semiconductors (ITRS)

Intel processors fall within the TRS power road map window100 W+ processors in 2006

200

175

150

125

100

75

50

25

01998 2000 2002 2004 2006 2008 2010 2012 2014

Pow

er (W

)

ItaniumTM ProcessorITRS High Performance CPU

x xx

x x x x xx

x

x

ItaniumTM 2 ProcessorITRS Cost-Performance CPU

Itaniumreg 4 Processor

Itaniumreg II Processor

Itaniumreg III Processor

page 12

High Currents Low Voltages hellip

Voltage scaling ~ 1V by 2006Current scaling to 100-175 A ~ 2006-2009Power delivery system impedance dropping below 1 mΩ ~ 2008

2000 2002 2004 2006 2008 2010 2012 2014

250

200

150

100

50

0

300

125

1

075

05

025

0

15

Icc

(A)

Year

Vcc

(A)

x xx x

x x

x

x

IccHigh-Performance CPU

Icc Cost-Performance CPU

Vcc

Currents Calculated form ITRS 2001

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics7

page 13

Power Conversion and Control Technology

Time High dVdt and dIdt (Faster Switching)

Voltage Lower voltage top reduce power losses

Power Higher power for distributed computing

page 14

CPU Power Losses Reduction Schemes

winding resistancecopper 06 Ohmsmil ftaluminum 1701 Ohmsmil ft

Power Losses Reduction SchemesVoltage ScalingSOI Silicon-On-InsulatorCopper Interconnect Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics8

page 15

Technology Challenge

Market Driving ForceMake it more intelligent (Easy to Use)

Make it operate faster

Make it smaller

Make it more efficient

Make it cheaper (Can be Use)

High-Speed is Essential

Powering High-Speed mP amp DSP

page 16

Component Solution Component Size Reduction

SMT Component

Size

080506030402

0201

12mm3mm

NACxx SERIES SMT ALUMINUM ELECTROLYTIC CAPACITORS

NRC SERIES CHIP RESISTORS

NMC SERIESCERAMIC

CHIP CAPACITORS

0201 bull

0201

bull

NINNIS SERIES CHIP INDUCTORS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics7

page 13

Power Conversion and Control Technology

Time High dVdt and dIdt (Faster Switching)

Voltage Lower voltage top reduce power losses

Power Higher power for distributed computing

page 14

CPU Power Losses Reduction Schemes

winding resistancecopper 06 Ohmsmil ftaluminum 1701 Ohmsmil ft

Power Losses Reduction SchemesVoltage ScalingSOI Silicon-On-InsulatorCopper Interconnect Technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics8

page 15

Technology Challenge

Market Driving ForceMake it more intelligent (Easy to Use)

Make it operate faster

Make it smaller

Make it more efficient

Make it cheaper (Can be Use)

High-Speed is Essential

Powering High-Speed mP amp DSP

page 16

Component Solution Component Size Reduction

SMT Component

Size

080506030402

0201

12mm3mm

NACxx SERIES SMT ALUMINUM ELECTROLYTIC CAPACITORS

NRC SERIES CHIP RESISTORS

NMC SERIESCERAMIC

CHIP CAPACITORS

0201 bull

0201

bull

NINNIS SERIES CHIP INDUCTORS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics8

page 15

Technology Challenge

Market Driving ForceMake it more intelligent (Easy to Use)

Make it operate faster

Make it smaller

Make it more efficient

Make it cheaper (Can be Use)

High-Speed is Essential

Powering High-Speed mP amp DSP

page 16

Component Solution Component Size Reduction

SMT Component

Size

080506030402

0201

12mm3mm

NACxx SERIES SMT ALUMINUM ELECTROLYTIC CAPACITORS

NRC SERIES CHIP RESISTORS

NMC SERIESCERAMIC

CHIP CAPACITORS

0201 bull

0201

bull

NINNIS SERIES CHIP INDUCTORS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics9

page 17

Power Supplying for PC mP amp Portable IA

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 18

Power Supplying for Microprocessor

Development of MicroprocessorsPower Dissipation Inside CPUCPU Power Losses Reduction SchemesPower Supply Voltage for Advanced MicroprocessorsRoadmap for Semiconductor Technology Developmentdidt Decoupling in Power Supplying for High-Speed microPsDRAM Power Supply Development TrendSwitching Frequencies Roadmap of SPSPossible Power Supply for Future (2010) MicroprocessorsTechnology Roadmap for Advanced SPS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics10

page 19

Power Supply for PC Mother Board

page 20

Power Supplying for Desktop PC and Servers

Typical Specifications

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics11

page 21

Two-Stage PFCPWM Control Scheme

Q1

PWM Controller

L

PFC Controller

CboostVout

+

ndash

VLINE

85-260VAC

PFC Converter DC-DC Converter

page 22

PFCPWM Combinational Control Scheme

PFC ControlSensing of Rectified Line VoltageSensing of Rectified Line CurrentSensing of Output DC-Link VoltageGeneration of PWM Gating Signal

Interface Circuit for PFCPWM Combination Control

PWM ControlSensing of Primary CurrentSensing of Output DC VoltageGeneration of PWM Gating SignalProvide DC Control Voltage

R2

R1D1

L1 D2 D3

Q1

C1

R3

R4R5

Q2

R6 T1D4

D5

C2

GND2

C3

AGND

PGND

PRIMARY SECONDARY

VOUT

+

ndash

VAC

+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics12

page 23

Lossless Soft Switching PFCForward Converter

ACDC PFC Converter DC-DC Forward Converter

page 24

ATX 203 Power Specifications

ATX 203 Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 8a 200W

16a 25a 10a 250W

20a 30a 12a 300W

ATX 12v Specifications

＋33V ＋5V ＋12V Rated Power

14a 21a 10a 200W

20a 25a 13a 250W

28a 30a 15a 300W

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics13

page 25

Inside the Switcing Power Supply

電源控制晶片

page 26

Components Used in a Switching Power Supply

(b) 電源濾波器

SU17V10100 （TOKIN）

(a) 薄膜電容01 microF250V

（神榮工業LHX系列UL規格）

(b) 陶瓷電容

2000pF(4700pF)AC250V

松下電子部品LS系列規格）

(e) 電解電容330 microF250V

(f) Power MOSFET

(i) Schottky diode

(k) 電解電容8200 microF10V

(l) 電解電容

1200 microF12V

(j) 抗流圈

(h) 磁放大器

TMCU05V10RC（TDK）

(c) 二極體

D3SBA40 （新電元工業）

(g) 絕緣變壓器

(自行製作）

參考資料最新交換式電源技術手冊

+ ++

++~

~

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics14

page 27

電流瞬間變化下的電源電壓暫態響應

trace 1

trace 2

trace 1 4Adivtrace 2 100mVdiv

84 86 88 90 92 94 96 98 2001

1

10

100

microsSwitching Regulator

Linear Regulator

Year

電源供應器反應時間的演進電流瞬間變化下的電源電壓暫態響應

page 28

Powering PC

Processor PowerDelivery

PowerSupplyPowerSupply

VRM

VRM

AGP

PCI

Memory

CPU

33V

12V 17V

25V12V

12V33V

5V

33V

5V

12V

ACAC

PC Mother Board

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics15

page 29

Power Supplying for Microprocessor

Pentium IV 5500萬顆電晶體 13 microm32GHz 17VRated 92W Peak 110W

New specs demand new power solutions

Intel Pentium IV

page 30

The Pentium IV Consumes and Dissipates a Lot of Power

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRMSupplying power to Pentium IV we need

A very large and high quality heat sinkWe even need a fan for force coolingWe also need a VRM to supply high current (70A) at low voltage (17V) with high current slew rate (50Amicrosec)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics16

page 31

didt Decoupling in Power Supplying for High-Speed microPs

PowerSupply

48 V

Die

Package

Local Board

Bulk Board

lt 4000Amicroslt 1000Amicros

lt 04Amicroslt 50Amicros

DCDCMODULE

(VRM)

page 32

DRAM Power Supply Voltage Development Trend

18V25V

25V25V25VRDRAM

18VTBDmdashmdashDDR II SDRAM

25V25V25VmdashDDR SDRAM

TBD18V 25V

(18V)18V 25V

(18V)mdashMobile RAM

33V33V33V33VSDRAM512Mb256Mb128Mb64Mb

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics17

page 33

Intel PC Mother Board Specs for 2004-2005

Power Supply Specifications for Intel CPU (2004-2005)

Source DigiTimesLab (20043)

115W

Tejas-C(65nm)

3-32GHZ

103W

80A

91A

VRM10

FMB 15

ge36GHz(預計)ge32GHzle3GHz處理器時脈

125W115W89W設計功率

(TDP)

101A68A設計電流量

(IccTd)

119A78A最大瞬間電流

(IccMax)

VRM10VRM9VRM Spec

Tejas(90nm)

FMB 20FMB 10原始名稱

PerformanceFMB2005

PerformanceFMB2004

MainStreamDMB2004

最新規範

page 34

Market Trends Device Requirements

Processor Power (Watts)

Supply Current (Amperes)

Nominal Supply Voltage Range (Volts DC)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics18

page 35

Market Trends Power Requirements

Processors memories ASICMuch faster load transients didt to 2000AusHigher load steps 20A to 100A and beyondLower transient tolerance maintain regulationTighter regulation from 5 to 2 for all conditions

Increased power consumptionBoard level drains from 200W to 1kWMid to high range servers from 5kW to 40kW

Need to fit system packaging constraints20mm board spacing for telecomMinimal board real-estate for datacom

page 36

Summary of Power Delivery Issues

Lower operating voltageHigher currentsTighter regulationHigher powerHigher didtNeeds for hot-swapLocalized protectionDistribution lossesQuantity of loads

Performance Criteria

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics19

page 37

Microprocessor Power-Supply Specifications From Intel

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 38

Microprocessor Power-Supply Specifications From Intel

bull VRM 80 (for Pentium Pro)bull VRM 81 (for Pentium Ⅱ order number 243408-001 May 1997)bull VRM 82 (for PentiumⅡ and Ⅲ and Celeron replaces VRM 81

order number 243773-002 March 1999)bull VRM 83 (for PⅡ and Ⅲ Xeon order number 243870-002 March 1999)bull VRM 84 (for processors with 155 V nominal supply voltage)

VRM (Voltage Regulator Module) dcdc converter design guidelines

Processor data sheets

bull Pentium regⅡ XeoonTM (order number 243772-001 June 1998)bull Pentium reg Ⅲ (order number 245085-001 March 1999)bull Pentium reg Ⅲ XeoonTM (order number 245095-001 March 1999)

Processor power distribution guidelines

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics20

page 39

Specifications-1

PentiumⅡ(28 V)

bull Output voltage (core) 28 Vnom18 to 28 V (5 bit VID)bull Output current 08 to 142Abull Static output voltage regulation -60 mV to + 100 mV bull Transient output voltage regulation -130 mV to + 130 mV bull Load current slew rate 30Amicros

PentiumⅡand Ⅲ (2 V)

bull Output voltage (core) 20 Vnom18 to 205 V (5 bit VID) bull Output current 08 to 161Abull Static output voltage regulation -60 mV to + 70 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

page 40

Specifications-2

Celeron

bull Output voltage (core) 20 Vnom 13 to 205 V (5 bit VID)bull Output current 08 to 122Abull Static output voltage regulation -89 mV to + 100 mV bull Transient output voltage regulation -144 mV to + 144 mV bull Load current slew rate 20Amicros

PentiumⅡand Ⅲ Xeon

bull Output voltage (core) 20 Vnom 18 to 28 V (5 bit VID) bull Output current 08 to 146Abull Static output voltage regulation -60 mV to + 60 mVbull Transient output voltage regulation -100 mV to + 100 mVbull Load current slew rate 20Amicros

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics21

page 41

Additional Specifications

Overshoot at turn-on or turn-off max 10

Input voltage +5 V +12V

Load current transition frequency 100Hz to 100kHz

OVP 110 to 125

Short-circuit protection

Current sharing function

Transient recovery time 100 micros (was 2 micros)

Maximum input current didt 01 Amicros

Efficiency min 80 at full loadmin 40 at 05 A load

page 42

Future Specifications

Input voltage 33 V 5V 12V ac line

Output voltage 15 V type 1 V to 2 V

Max output current up to 60 A

Load current slew rate at processor decoupling capacitors 1-5 Ans

Output voltage tolerance plusmn 2 same static and transient regulation

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics22

page 43

Voltage Identification (VID) Codes

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

000

00

00000

000000

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

175170165

155160

135130

140145150

180185190195200205

Processor Pins0 = Connected to Vss

1 = Open or pull-up to Vin

VccCOREor

Vcc L2

VID4 VID3 VID2 VID1 VID0 (VDC)

111

11

11111

111111

001

11

11111

000000

110

00

11110

110000

110

10

11001

001100

010

01

10101

101010

302928

2627

2221

232425

313233343536

page 44

Intelreg Pentiumreg IV Microprocessor Power Trend

Within Intelreg Pentiumreg 4 generation power increases by 30 Watts and Current increases by 30 Amps

Source wwwtomshardwarecom

2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Pentiumreg 4_lcc

Pent

ium

reg4_

lcc

(A)

Pentiumreg 4_power

Pent

ium

reg4_

Pow

er(W

)

100

95

90

85

80

75

70

65

60

55

50

70

65

60

55

50

45

40

35

30

25

20

Frequency (GHz)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics23

page 45

Fast Dynamic Response for Step Load Changes

page 46

Distributed Power Supply

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics24

page 47

Power Supplying for PC and Servers

Graphicscontroller

Peripheral 3

Peripheral 2

Peripheral 1

DDR-QDRMemory

Peripheral N

Bridge

Microprocessor

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

Power supplyPower supply

page 48

Power Supplying Architecture

Redundant Central (Bulk) Redundant amp Fault Group ConfiguredRedundant Central (Bulk)

CircuitModular

+5V

+12V

AC-DC

AC-DC

N+1

N+1

AC-DC

AC-DC

AC-DC+12V

Batteryreserve

+15V+15V+12V

+33V+25V

Ringinggenerator

+25V

+5V +5V+12V +12V 1+1

Partially (Hybrid) Distributed

Fully Distributed

Dis

tribu

tion

Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics25

page 49

Characteristics of the Central Bulk Solution

Benifits DrawbacksLowest Cost lt 1kWAdequate performanceCompactConversion off boardsEfficientSimple to implementBest for small systems

Custom designSingle regulation point Distribution losses Transient responseORrsquoing Diodes lossy+5V 300mV 6+33V 300mV 8+25V 300mV 12Difficult to hot-swapInrush limitingFuses or other interruptEMIEMCHigh cost at gt 1kW

Circuit Modules

Backplane

Central Power Supply

-V

+V

page 50

Characteristics of Distributed Solutions

Availability designed into systemrsquos failure groupIntegrated into functional board developmentEliminates need for redundancySeamless upgrades

Facilitates point-of-load regulationSatisfies performance demandsMinimizes distribution losses

Simplifies system designBackplane distribution and protectionCircuit isolationIndependent board performance

Off-shelf availability minimizes riskStandard components amp multiple vendorsRemoves power from critical path

ScaleabilityUpgreadability

GrowthReuseSpeed

StandardizationCost

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics26

page 51

Distributed Power Architecture

CPU

System unit

DC-DC converter

(D2D)

Front end power system

AC input

+48Vpower

bus

Front end power

PWM IC

Front end powerInternet

DCDC Converter

25V

33V

5V

12V

Total Output Power = 125WEfficiency gt 85 Maximum LoadSize 38rdquo times 19rdquo times 05rdquoLoad regulation lt 2Current Limit 120Temperature -40degC - 80degC

PWM IC

page 52

Circuit Architecture of a Distributed Power Supply System

10-20 Arectifiers

100-200 VMOSFET

BYV26BYV27 series diodes

33512VDC

Low Med ium Po wer ForwardFlyback Converter

15-30 Arectifiers

100-200 VMOSFETs

33512VDC

Medium Po wer Half Bridg e DCDC Converter

406070 Arectifiers

33512VDC

100-200 VMOSFETs

Low Voltage High Po wer Bridge DCDC Converter

406070 Arectifiers

High Voltage High Po wer Full Br idgeACAC Converter

400-600 VMOSFETs

Po wer F actor Correction (PFC)

2448 VDC

400 VDC

100200 VAC

Boos terDiode

400-800 VMOSFET

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics27

page 53

Distributed Power Architecture

page 54

Distributed Power Supply

Changes in technology are APPLICATION drivenhellipndash Distributed Power Supplies

50V 100A

withPFC

PRE-REGULATORS

Power Factor Correction

High power densityon board converters

Soft switching techniquesLow voltage converters (1V)Planar magnetics

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics28

page 55

Distributed Power Systems amp Architecture

Pre-regulator

PowerFactor

Correction

High Volt VRM

On-boardConverter

ConverterOn-board

Low Volt VRM

Testbed Partnersbull Intelbull IBMbull Artesyn Technologiesbull Celestica

60HzAC

Voltage Regulator Module (VRM)

Processor

page 56

Selection of the Bus Voltage

Probably one of the most critical performance and price drivers It influences

Availability of standard components

Distribution losses

Aggregate corporate usage

Will determine ease of reconfiguration into different market segmentsCentral office

Europe and Asia

Embedded infrastructure

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics29

page 57

Some Possible Bus Voltage Levels

+350Vdc Deployed by some high-end systems+140Vdc early telecom systems phased out raquo 10yrs+48Vdc Intel proposed Server Strategic Initiative+24Vdc Telecom Wireless+12Vdc Intel proposed low-end servers (SSI)+33Vdc Test equipment manufacturer-48Vdc Telecom switching amp transmission-60Vdc Some European telecom officesHigh frequency ac Latest concept

page 58

+48V Distributed Architecture (SSI Server System Infrastructure)

Commercial AC Input

AC Distribution

+48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

DC Distribution

+48V Intermediate Bus

DC

DC

DC

DC

DC

DC

DC

DC

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics30

page 59

+48V Distributed Architecture

+48V Distributed (432-528Vdc)

lt High cost of accommodation DC input systems

lt Requires development amp very costly isolation converters in place of acdc for telecom

lt Cannot accommodate internal DC backup (voltage range insufficient)

lt Limited set of dcdc converters in existencelt Costlier bus protection strategy

lt Low cost DCDC converterslt Meets SSI Initiative guidelines (lower

cost components)lt Costs not constrained telecom

requirements

DrawbacksBenefits

page 60

-48V Telecom Range Distributed Architecture

Commercial AC Input

AC Distribution

-48V Intermediate Bus

AC

DC

AC

DC

AC

DC

AC

DC

Central Office -48VDC Input

EMI Filter

-48V Intermediate Bus

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics31

page 61

-48V Telecom Range Distributed Architecture

-48V Distributed (-36 to -60Vdc[-75dc])

lt Somewhat costly when majority of applications are AC powered with external energy reserve

lt Wide DC bus voltage range complicates design of DC to DC conversion (cost efficiency tradeoff)

lt simple design for cross market compatibility

lt Lowest total cost solution for DC central office powered systems

lt Accommodates internal battery backuplt Bus protection is simpler to achievelt Internal backup is possible

DrawbacksBenefits

page 62

Fault Tolerance and Hot Pluggability

Input placed protection and control is much simpler and easier

Output regulation is not affectedMuch lower distribution lossesEmissions containment added without affecting performanceLow dissipation inrush protection

DCDC Converter

OnOff

VIn(+)

VIn(-)

CInQinrush

Rinrush

Cfuse

Fin

EMIInrush

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics32

page 63

Powering Architecture Evolution for CampC Equipments

Multi-OutputACDC Power

Supply

Multi-OutputACDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

Multi-OutputDCDC Power

Supply

Multi-OutputDCDC Power

Supply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

ACDC PowerSupply

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

DCDCConverterDCDC

Converter

POLDCDCConv

POLDCDCConv

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

TELECOM

COMPUTING

1970rsquos 1980rsquos 1990rsquos 2000+Time

Centralized

Distributed

Powe

ring

Arc

hite

ctur

es

page 64

Summary of Distributed Power Supply

A distributed solution may be the only answer due to the migration toward lower voltages tighter regulation amp higher currents These applications dictate close proximity between power conversion and the load

Distributed power enables easy migration growth and enhancement among voltage rails as changes in voltage levels and semiconductor requirements evolve

Distributed power is a cost effective solution for the power delivery system especially entry level systems

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics33

page 65

Voltage Regulation Module (VRM)

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 66

Realization of Buck Regulator (VRM)

Vdc vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

Intel Pentium IV

Pentium IV5500 Tz013 microm 32GHz17VRated Power 92WPeak Power 110W

VRM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics34

page 67

VRM Industry Consortium

Intel Pentium

1000

200

MHzProcessor Speed

Year1995 2000 2005

AB

C

D

12 ~ 18 V 50 A

26 ~ 33 V 12 A

SystemPower Supplies Components

Intel Delta Electronics Texas Instruments

International RectifierNational SemiconductorSTMicroelectronics

page 68

VRM Design Concept

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics35

page 69

Dynamic Response output capacitance size and cost

page 70

Cap Required vs Dynamic Response

Low inductance and fast control are required

Ideal Capacitor

Real Capacitor

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics36

page 71

Transient Response vs Output Capacitor Technology

page 72

Output Capacitance vs Inductance

Given the load current

Minimum inductance and and fastest control are needed for the present capacitor technology

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics37

page 73

Integrating VRM on the Cartridge

IntelIntelProcessorProcessor

VRM ModuleVRM Module

VRMVRMModuleModule

IntelIntelProcessorProcessor

Source SPEC VPI amp SU USA

page 74

Point-of-Load (POL) Conversion Choices

Custom processor power100W - 56Vin12 - 20 4 bit programmable55 Amps

Standard processor powerTitania Divisionup to 30AParallelableOutput 5 bit VID programmable

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics38

page 75

Vicor AC-DC and DC-DC Modules

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 76

Vicor AC-DC and DC-DC Modules

httpwwwvicrcom

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics39

page 77

AC-DC and DC-DC Modules for Distributed Power

300V DC Power Bus

page 78

Typical Connection of the Input AC Module (No PFC)

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erter

+In

Gate in (PC)

Gate out (PR)

-In

Vicor DC-DCConv erterFilter

C3

F1C1R1

C2R2

C7

C5

F2

D1

D2

C6

C8

V1

V2

Z1

N

ST

L -V

+V

ENBOKVI-ARM

820micro F HUB820-S 2200microF HUB2200-S1200micro F HUB1200-S 2700microF HUB2700-S800micro F HUB1800-S 3300microF HUB3300-S

Holdup Box (HUB)

03040MOVZ1

Film Cap 08micro fC78

00670DiodeD12

021783A PC TronF12

13755220V gas tubesV12

00127-1503150kΩ 05WR12

010004700pFC3-6

see textHoldup capacitorsC12

VicorPart NumberDescriptionPart

Sizing PCB tracesAll traces shown in bold carry significant

current and should be sized accordinglyVI-ARM- 12

NSTL 10A rms at 90Vac and 500W+- In 4A DC at 190Vdc and 750W

VI-ARM- 22NSTL 20A rms at 90Vac and 1000W+- In 8A DC at 190Vdc and 150W

bull Required if C1 amp C2 are located more than 6 inches from output VI-ARM

To additional modules

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics40

page 79

VI-ARM AC-DC ModuleAutoranging Rectifier Module

FeaturesAutoranging inputMicroprocessor controlledVI-ARM-_12 500 Watts 90-132Vac 750 Watts 180-264VacVI-ARM-_22 1000 Watts 90-132Vac 1500 Watts 180-264VacVout 28-375 Vdc96-98 Efficiency100degC baseplate (no derating)UL CSA TUV VDE BABTAC Bus OK module enableInrush limiting (no external circuitry)CE MarkedSize 579 x 368 x 127 mm

page 80

DC-DC Modules from VICOR

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics41

page 81

VI-Maxi DC-DC Module300Vin 48Vout 500Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 48VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 90Maximum operating temperature 100degC at full loadPower density 99Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize117x56x127 mm

page 82

VI-Mini DC-DC Module300Vin 33Vout 264Watts

FeaturesDC input range 180 - 375VInput surge withstand 400V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn02 no load to full loadEfficiency 80Maximum operating temperature 100degC at full loadPower density 52Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117 x 56 x 127 mm

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics42

page 83

VI-Micro DC-DC Module300Vin 2Vout 50Watts

FeaturesDC input range 180 - 375VInput surge withstand400V for 100msDC output 2VProgrammable output 10 to 110Regulation plusmn05 no load to full loadEfficiency 70Maximum operating temperature 100degC at full loadPower density 30Wcubic inchHeight above board 043 in (109 mm)Parallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 579 x 368 x 127 mm

page 84

48V DC Bus DC-DC ConvertersEMI Filtering Inrush Limiting and Transient Immunity Using Three-Stage Solution

Input Power Conditioning Module

Input Filter Module DC-DC Module

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics43

page 85

DC-DC Module48Vin 33Vout 264Watts

FeaturesDC input range 36 - 75VInput surge withstand 100V for 100msDC output 33VProgrammable output 10 to 110Regulation plusmn03 no load to full loadEfficiency 795Maximum operating temperature 100degC at full loadPower density 52Wcubic inchParallelable with N+M fault toleranceLow noise ZCSZVS architectureSize 117x56x127 mm

page 86

Configurations of DC-DC Converters

DC-DC Converter48V in 5V 30A out

48V in12V 8A out

300V in12V 8A out

Front EndACDC Module

300 Watts

EMIFilter

plusmn12V 8A

5V30A48V

48V in33V 3A out

48V in33V 5A out

33V 10A

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics44

page 87

Parallel of DC-DC Converters

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+OUT+S

TRIM-S

-OUT

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT-IN

+IN

GATE IN

GATE OUT

-IN

DC-DC Converter 48Vin

33VVout150W

Load

+

-

INPUT

DC-DC Converter 48Vin

33VVout150W

DC-DC Converter 48Vin

33VVout150W

page 88

PFC AC-DC Switchers

FeaturesNear unity power factorEN61000-3-2 harmonic current complianceLow profile packageOutput power to 1500WUp to 6 user specifiable outputsUniversal AC inputPower density up to 11Win3

Integral cooling fansNew ldquoAutosenserdquo featureSafety agency approvals UL CUL TUV VDE CE Marked

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics45

page 89

PFC AC-DC Switchers from VICOR

page 90

Buck DC-DC Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics46

page 91

Buck Converter

io DVV = L(AVG)o II =

Waveforms in Continuous Inductor Current

IQ1 = ia

ICR1 = iP

IL SolidiO Dashed

VC-P SolidVO Dashed

TON TOFF

TS

∆ IL

L

ONState

RL

a c

P

+R

CIL = ic

ia RDS(on)

RC

VO

VI

OFFState

RL

a cL

P

+R

CIL = ic

ia

RC

VO

VI Vd

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

page 92

Buck Converter in Discontinuous Conduction Mode

C

RL

Vi

iL

dTs d2Ts (1-d-d2)Ts

iLIP

IO

t

t

Vi ndash Vo

ndash Vo

vL

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics47

page 93

Boundary Condition for Discontinuous Inductor Current

Define the ldquocritical load current rdquo for continuous conduction operation as Io(crit)

During the DCM period the inductor is disconnected from the output capacitor

Lo(Crit) II ∆=21

Inductor Current Boundary Condition

Discontinuous Inductor Current

RL

a cL

P

+R

CIL = ic

ia

RC

VOd s

g CR1

Q1

VI

Driv eCircuit

IL SolidiO Dashed = iO(Crit)

∆ IL

TON TOFF

TS

IL SolidiO Dashed

∆ IL

D2TS

TS

0

0

D3TSDTS

page 94

Typical Waveform in Discontinuous Conduction Mode

2

io

DK411

2VVtimes

++times=

STRL2K

timestimes=

In DCM operation the voltage conversion relationship is a function of the input voltage duty cycle power stage inductance the switching frequency and the output load resistance while for continuous conduction mode

IQ1

ICR1

IL SolidiO Dashed

VC-P SolidVO Dashed

TS

D3TSDTS

IPK

IPK

∆ IL

D2TS

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics48

page 95

Minimum Inductance to Guarantee CCM Operation

What is the Critical Inductance to guarantee CCM operation for the critical load current

L(Crit) =

o(Crit)

Si(max)

oo

min I2

TV

V1VL

times

times⎥⎥⎦

⎤

⎢⎢⎣

⎡minustimes

ge

o(Crit)

OFF(min)LLiomin I

T)RIV(V

21L timestimes++timesge

Solving Lmin with Vi(max) we get the Critical Inductance

LI

TON TOFF

TS

∆IL0

DriveCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic

+

page 96

Voltage Gain at CCM and DCM Modes

id

+

minus

Vd

iL

LvL

+ minus

vo

+

minus

io

C R

low-pass filter

ic

iS

iD

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =CCM

DCM

How to interpret its physical meaning

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics49

page 97

DC Voltage Gain in CCM and DCM

d

o

VV

Vd = constant

)(maxLB

o

II

LVTI ds

LB 8max =

Step-down converter characteristics keeping Vd constant

0 05 10 15 20

0

025

050

075

10

DCM

D = 10

01

03

05

07

09

CCM

)(41

max2

2

LBod

o

IID

DVV

+=

DVV

d

o =

The buck converter has a tendency to increase its voltage gain when operating in DCM

page 98

Key Parameters in the Design of a Buck Converter

SpecificationsDC-link VoltageRated Output VoltageRated Output CurrentRipple Inductor CurrentOutput Ripple VoltageHoldup TimeSurge Load Current

Design ParametersMaximum Duty RatioCritical Load CurrentCritical inductanceAverage Inductor CurrentInductor Current RipplePeak Transistor VoltagePeak Transistor CurrentRated Transistor CurrentPeak Diode VoltagePeak Diode CurrentRated Diode CurrentOutput Filter CapacitanceOutput Filter ESR

Driv eCircuit

RC

R

VORL

L

Vl

ia

Q1

CR1

ca

g

p

d s

clL = ic+

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics50

page 99

A Review of DC-DC Converter Topologies

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

page 100

Converter Topologies

Single-Phase Buck Converterwith free-wheeling diodewith synchronous rectifier

Interleaved (Multi-Phase) Buck ConverterTransformer-Coupled Converters

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics51

page 101

Buck Converter with Free-Wheeling Diode

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Control

page 102

Buck Converter with Synchronous Rectifier

Control

+5V or +12V

microPSilver box Input filter

didt limiter

+ +

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics52

page 103

Comparison

Buck with FWD Buck with SR

Conduction loss at full load

Conduction loss at light load

Switching loss

Control and drive complexity

OVP capability

higher

lower due to DCM

lower

none

lower

lower

Higher due to lack of DCM(unless SR disabled)

higher

yes by tuming on SR

higher

page 104

Quantitative Relationships

DC input current

AC input rms current

MMS current in upper switch

Negative current slope in buck inductor

RMS current in SR switch

Positive current slope in buck

( )2

2

2

rmsacin 121 D

IIDII

oo minus⎟⎟

⎠

⎞⎜⎜⎝

⎛ ∆+=

( ) DII o=dcin

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+= 2

2

rmssw 121

oo I

IDII

LVV

dtdi ominus

= in1

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+minus= 2

2

rmsSR 1211

oo I

IDII

LV

dtdi ominus

=2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics53

page 105

Comments

Large input ripple current

Limited rate of change of current in the buck inductor sluggish load transient response

Current capability limited by device availability and size (footprint and height) restrictions

Possible solution interleaved operation of several identical buck converters

page 106

Two-Phase Interleaving

Control

microPSilver box

+ ++

L3

C2

S1

S2

L1

C1

S3

S4

L2v1(t)v2(t)v3(t)v4(t)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics54

page 107

Typical Waveforms

48000 48500 49000 49500 50000000200400600800

10001200

135014001450150015501600

400500600700800900

11001000

Time ( micros)

I(L1) I(L2)

Iindsum

I(in)

page 108

Four-Phase Interleaving

Control

microPSilver box

+ ++

L5

C2

S1

S2 L3 C1

S3

S4

v1(t)v2(t)v3(t)v4(t)

L1

L2 L4

v5(t)v6(t)v7(t)v8(t)

S5

S6

S7

S8

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics55

page 109

Typical Waveforms

300400500600700800900

132013401360138014001420

150200250300350400

500450

198000 198500 199000 199500 200000Time(micros)

I(L1) I(L2) I(L3) I(L4)

Iindsum

I(in)

page 110

Comments

Benefits

Most significant reduced rms current in the input filter capacitor rarr smaller and less expensive input capacitorDistributed heat dissipation rarr higher power capability Increased equivalent frequency without increased switching losses rarrsmaller equivalent inductor rarr larger didt of the current flowing toward the output rarr shorter transient timeSmaller output capacitor

Disadvantages

More switches and output inductorsComplex controlAsymmetrical current sharing in VMCMore than one current sensor in CMC (when the conductiontime of the upper switches overlap)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics56

page 111

Transformer-Coupled Converters

Advantages

higher input voltage possible without reduced duty ratio rarrreduced switch current rarr reduced switch lossesreduced input current rarr reduced distribution and front-end lossesoptimized duty ration rarr reduced input and output ripple ripplecurrent rarr easier filtering

Disadvantages

More switchesMore magneticsComplex control

page 112

Candidate Topologies

Input sidehalf bridgefull bridgepush-pullforward with RCD resetforward with active clampinterleaved forward

Output sidehalf-wave rectifierpush-pull rectifier with center tapped secondarycurrent-doubler rectifierswitching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics57

page 113

Input-Side Circuit Topologies

+ ++

+ + +

half-bridge full-bridge push-pull

forward with RCD reset interleaved forward with RCD reset forward with active reset

page 114

Output-Side Circuit Topologies

microP+

microP+

microP+

microP+

half-wave rectifier push-pull rectifier

current-doubler rectifier push-pull rectifier with switching post-regulator

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics58

page 115

Input-Side Circuits-Comments

Drive simplicity forward with RCD reset push-pull (ground-referenced drive)

Optimum switch duty ratio

Minimum number of switches

Optimum input duty ration

interleaved forward with RCD reset (100 nominal DR is possible)

forward with RCD reset

forward with active clamp single forward and interleaved forwardwith RCD reset (50 nominal DR and close to 100 DR during load transient is possible)

page 116

Output-Side Circuits-Comments

Drive simplicity

half-wave rectifier current-doubler rectifier (ground-referenced SR switches

Largest step-down ratio

Minimum number of high-current terminations

Minimum number of components

half-wave rectifier push-pull rectifier

half-wave rectifier

current-doubler rectifier

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics59

page 117

Some Low-Cost High-Performance DC-DC Converter Topologies

+ndashVin D2

D1

G

S

LoadC0

L0

+ndashVinD2

D1

G

S

LoadC0

L0

1 This circuit represents a conv entional buck converter

3 Combining the buck conv erter topology with the buck-boost conv erter topology results in this circuit

+ndashVin L0

D1

G

S

LoadC0

2 Shown here is a conventional buck-boost converter

4 The output capacitor design in the new isolated dc-dc conv erter is the same as in the conventional buck or forward conv erter

+ndashVin

G

D2

D1C0 Load

S

T1

page 118

Synchronous Buck Converters

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics60

page 119

Buck Regulator for Low-Voltage Regulators

A buck (step-down) switching regulator is commonly used in applications such as powering microprocessors They are ideal for converting a 5V-system voltage to the 15V sim 2V or so at up to 20A and even to 60A that processors require

The main advantages of a buck regulator are high efficiency relatively simple design no transformer low switch stress and small output filter The main disadvantage is possible over voltage if the main switch shorts

vo(t)C+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

page 120

Synchronous and Non-Synchronous Buck Converter

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

To reduce the diode voltage drip in low-voltage conversion the diode is replaced with a synchronously controlled active switch In ideal condition these two switches are switched in complemenrary

Q1

Q2

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics61

page 121

Realization of Buck Regulator

Vbat vo(t)C+minus

+

minus

IloadiL(t) L1

2++

minus

minusvL(t)

vsw(t)

ic (t)

R

vi vo

L

CD

+

minus

+

minus

BASIC BUCK CONVERTER SYNCHRONOUS BUCK CONVERTER

vi vo

L

C

+

minus

+

minus

Lithium Ion Battery Low Power mP

page 122

Gate Drive and Current Waveforms under CCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics62

page 123

Gate Drive and Current Waveforms under DCM Mode

vi v o

L

C

+

minus

+

minus

T2

clock

Vgate1(Q1)

Vgate2(Q2)

ID(Q1)

IS(Q2)

IL

T1

NoteDuring the zero induction current period both the switches Q1 and Q2 must be turned off

page 124

Light-load Operation CCM and DCM

withoutzero crossdetect

withzero crossdetect

iL(t)

t

high Io

low Io

Inductor current reverses polarity at high loads

iL(t)

t

high Io

low Io

Inductor current drops to zero before the end of the cycle ldquoDiscontinuous conduction moderdquo (DCM)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics63

page 125

Implementing Zero-Crossing Detection

With the zero-crossing comparator the switch S2 operates as a diode resulting in DCM and improved efficiency at light loadsFor example PWM regulators from National Semiconductors in the LM26XX family have this feature

+minus

+

v(t)

ndash

IoLiL(t)

S2Vg

S2Control

logic

S2 is turnedOFF

C

iC(t)vL(t)+ ndash

S2

S1

page 126

CCM vs DCM

In DCM the inductor current is always positiveAt light loads in DCM the duty cycle is significantly lower than in CCMCCM operation at light loads is undesirable because the reversal of the inductor current polarity contributes to conduction losses while it does not contribute to the output load currentWith a diode rectifier DCM operation occurs automatically because of the diode characteristicWith a synchronous rectifier DCM operation at light loads can be accomplished by turning off the NMOS switch at the zero-crossing of the inductor current

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics64

page 127

LM2651 15A High Efficiency Synchronous Switching Regulator

Ultra high efficiency up to 97High efficiency over a 15A to milliamperes load range4V to 14V input voltage range18V 25V 33V or ADJ output voltageInternal MOSFET switch with low RDS(on) of 75mW300kHz fixed frequency internal oscillator7microA shutdown currentPatented current sensing for current mode controlInput undervoltage lockoutAdjustable soft-startCurrent limit and thermal shutdown16-pin TSSOP package

FEATURES

(VIN = 5V VOUT = 33V)

page 128

L2651 Block Diagram

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics65

page 129

LX1669 Control of a Synchronous Rectifiers

5V

C81microF

C31microF

12V

TDRVVCC12

VCC5

PWGGDOVPVID0VID1VID2

PGNDBDRVAGNDSSEN

FFB

VCCRE

VID4VID3

12345678

161514131211109

VID4VID3VID2

VID1

VID0

L2 1microF

Q1IRL3102

Q2IRL3303

L125microF

C21500microFx3

RSENSE

25mΩCPU Core

VCORE

C11500microFx6

Q4SCR

2N6504R310kΩ

01microFCSS

LX16

69

page 130

Multi-Phase DC-DC Converters

Ref ldquoA Two Stage Voltage Regulator Module with fast transient response capabilityrdquoP Alou JA Cobos R Prieto O Garciacutea and J Uceda PESC 2003

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics66

page 131

Motivation

page 132

Current Speed in a Buck Converter

Output inductance fixes maximum current slew rate

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics67

page 133

Current Speed in a Buck Converter

To compare the dynamic response not only the current speed but also the current ripple should be regarded

⎟⎠⎞

⎜⎝⎛

dtdi

I∆

page 134

Current Speed in a Buck Converter

If VIN gtgt VOUT Small Duty Cycle

Asymmetric response ⎟⎠⎞

⎜⎝⎛

dtdi gt ⎟

⎠⎞

⎜⎝⎛

dtdi

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics68

page 135

Multiphase Buck Converter

page 136

Multiphase Buck Increasing VIN

Ripple cancellation is negligibleAsymmetrical transientSwitching losses very high

High VIN combined with high IOUT

Drawbacks

In general the multi-phase buck converter is not suitable for high input voltage to low output voltage conversion

5V 12V

14V 48V

3V

3V

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics69

page 137

Can Multiphase Buck still be useful at 24V 48V

Multiphase Buck converterSymmetric operation d=50Good Ripple cancellationSmaller switching lossesHigh VIN combined with low current (Ioutn)

page 138

DC-DC Current Transformer

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics70

page 139

Influence of turns ratio n1

Turns ratio adapts voltage and current levels to operate at 50

page 140

DCDC current transformer Current fed Push-Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics71

page 141

DCDC current transformer Current fed Push-Pull (50)

fsw does not affect dynamic responseMinimum fsw fixed by

Core saturationMagnetizing Current Ripple (Secondary)

page 142

Design 2 Phase Buck + Current Fed-Push Pull (50)

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics72

page 143

Half Bridge and Multiphase Half Bridge (2 and 3 phases)

page 144

Comparing with Other Solutions

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics73

page 145

Losses comparison Two stages vs Half Bridge

page 146

Losses comparison Two stages vs Multiphase Half Bridge

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics74

page 147

Summary

Two stage approach alternative solution to improve the dynamic response response

It combines Multiphase Buck advantages + High VIN

Optimized output stage (50)Two stage solution present smaller losses than 1 Phase HB and 2 Phase HB for a 20Aμs ∆I=5A specification3 Phase HB reduces the losses at high current (gt50A) keeping a fast current slew rate (paralleling structure)

page 148

SPS Design A Systematic Approach

Power Electronics IC Design and DSP Control Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC Design amp DSP Control Lab

國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics75

page 149

Functional Block Diagram for a PWM Switching Power Supply

RFI filter and surge

suppression

Input rectifiers

and filtering

Start-up IC supply amp drive

bias circuit

Power switches

Controller

Transformer Rectifiers and filters

Protection circuits

Voltage feedback

circuit

Input

Ground

Vin(DC) Vout(DC)

Output

Ground

page 150

Design Procedure

Start

WhichTopology

Black Box Calculations

Design Specification Form

From general design requirement choose a switching regulator topology

Determine semiconductor parts and locate any trouble spots

Design transformer wire gauges etc

Design output indicators amp select rectifiers and capacitors

Design driver circuits

Choose control mode amp IC Design basic functions

Design Voltage feedback amp cross-regulation circuits

Transformer Design

Output Filter amp Rectifier Design

Power Switch amp Driver Design

Controller Design

Output Feedback Design

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics76

page 151

Design Procedure

Start-up Circuit Design

Protection Circuits Design

Higher Order Functions Design

Thermal Analysis amp Design

Breadboarding amp Physical Design

Test Operation vs Desired

Refine Design

EMIRFI Testing

Prepare for Production

Design start-up amp VCC circuits

Design required OV OC amp surge protection circuits

Design special interfaces and function (MCU PWR DWN etc)

Design required heatsink and heat removal considerations

PCB layout considerations and form factor considerations

Test all functions

Make modifications to designScreen room testing per approval body specification

page 152

Topology Selection Guide

Note CM Current Mode Control FF Feedforward Control

Non-isolated DC-DC Converter

For step-down Buck Continuous CMFor step-up Boost Discontinuous FF or CMFor Reverse polarityBuck-Boost Discontinuous FF or CM

Transformer Coupled DC-DC Converter

under 200 W Flyback Discontinuous FF or CM200 W - 1 kW Forward Continuous CMOver 1 kW Half Bridge Full Bridge Continuous CM

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics77

page 153

How to Select Topology of Output Converter in Off-Line SPS

ASSUMPTIONS1 Input voltage 120 to 400 VDC (which is typical for rectified AC line voltage or an output of PFC boost)2 Output voltages lt48V NOTE This is just basic guidance in selecting the proper SMPS topology which is based on the authors personal view The right topology will be selected depending on specific requirements for the power supply (including cost and time factors) and personal experience of the designer Po output powerIo maximum current of any output

page 154

AC

Power Supply ndash A Systematic Block Diagram

Input Power ConditioningPFCAVS

EMIFilter

BridgeRectifier

VoltageRegulator

Rectifier

RegulatorLinearSwitching

Transformer

Diode

Transformer

OPTOCoupler Feedback

OpAmp

Vref

DC

Transistor

PWM

SynchronousRectifier

Controller

PFC

Transistor

Diode

Primary side Secondary side

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics78

page 155

Primary Side Components Selection

Input Power ConditioningPFC

PFCController

MosfetTriac

Diode

Switcher

BridgeRectifier

OflineLinearRegulator

Transistor

PWMController

Trans for mer

Diode

Transistor

PWMController

StandbyAuxillarySwitcher

StandbyAuxillaryTransformer

Turbosw itchSTTA seriesSTTH806TTI (Tandem diode)STTH1506TPISTTHxxRxx (TurboII)

High Voltage MOSFETSTxxNBxx (NBNM series)STxxNMxx (MDmesh)STxxNKxx (Powermesh)IRFxxx

Snubber - STTB seriesDemagnetization - BYT seriesFreew heel - STTA series

UC284XUC384xL599XL499XL6565L6598VIPerXXXTSM007

PFCL4981ABL6561

VIPerXXXL6590

STBRxxx Bridge rectif iersDiode+SCR combinations for very high pow er

VB408VB409

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

ACEMI

Filter

Diode

Transformer

Transformer

page 156

Secondary Side Components Selection

VoltageRegulator

RegulatorLinearSwitching

OpAmp

Vref

DC

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

TL431TSxxxxTSMxxxLMxxx

Synch Rect DriversSTSRX

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Rectifier

SynchronousRectifier

Controller

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics79

page 157

Isolated DC-DC Half BridgeFull Bridge

DCPWM

HighSide ampLowSideDrivers

HalfFull BridgePower Supply

DC LINE

Primary SwitcherInput Control

UC284XUC384xL599XL499XL6598TSM007

High SideLow Side Drivers for Half BridgeFull Bridge PSL638x

Low Voltage MOSFETNH SeriesNF Series

New Copper Clip PackageNew Pow er SO-8 Package

Pow er Schottky (lt20V)STPS series

Low Voltage Ultrafast (gt20)STPR seriesBYW series

Synch Rect DriversSTSRX

SynchronousRectifier

Controller

Diode

Transformer

Transformer

page 158

Voltage Regulator

VoltageRegulator

DCDC

Convert a DC Voltage to other VoltagesProvide a Clean output Voltage

Controller

Linear Regulator

Not very efficient at higher currents Low noise

Switching Regulator

Very efficient Switching noise

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics80

page 159

Linear Voltage Regulators

Ultra low dropout low voltage regulatorL6932

Industry standard Low Dropout regulatorsL49xx L29xx L108x

Low dropout 5A op currentL495x

Low dropout regulators very low to upto few Amperes load

LDxx LFxx KFxx LKxx

General purpose =Ve amp -Ve op voltagesLM7xxx

DescriptionPart Numbers

Controller

Linear Regulator

page 160

Switching Voltage Regulators - 1

1A Boost Converter for Single Battery applications

L6920

1A Constant Current Battery Charger

L6902

Buck Converters 45 to 25V Ip 1 to 25A

L597x

Constant Current Battery Charger Controller

TSM108

15A40V Switching regulatorMC34063

600mA Step down converters for Battery based applications

L69256

5V Inverter 0275AmpST755

First Generation Buck convertersL496xL296

Buck converter 8 to 55V Ip 1 to 10A

L497x

DescriptionPart Numbers

Switching Regulators

33 to 5V Converter 30mAL667

5V to 12 V converter 30mAL662

DescriptionPart Numbers

Charge Pumps DC-DC Converters

Controller

Diode

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics81

page 161

Synchronous Rectification ICs

Controller 2 or 4 phase VRM controllers

L6918x

Single Phase Synch Buck Converter wide range

L69957

Dual PWM controllers with linear regulators

L5994

Controller VRM84 amp VRM85 with 0 or 1 or 2 Linear regulators

L691x

Controller VRM90 2 phase L6917B

Controller for 2 to 8 phase VRM applications

L6919x

HsLs Driver for VRM applicationsL6601

Controller 1 phase Synch Buck converter

L6910

DescriptionPart Numbers

Non Isolated MotherboardPoint-of-load Applications

Forward Topology Synch rectification driver

STSR2

Flyback topology Synchronous rectification driver

STSR3

DescriptionPart Numbers

Isolated Topologies

page 162

Selection and Placement of Decoupling Capacitors for High-Speed mP

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics82

page 163

Bypass and Decoupiling Capacitors

POWER

GROUND

minus

+

minus

+

minus

+

minus

+

Analog Circuit

Digital Circuit

Power Circuit

Bypass Capacitor

decoupling capacitor

page 164

Bypass Capacitor

The main function of the bypass capacitor is to create an AC shunt to remove undesirable energy from entering susceptible areasThe bypass capacitor is acting as a high frequency bypass source to reduce the transient circuit demand on the power supply unitAluminum or tantalum capacitor is a good choice for bypass capacitors its value depends on the transient current demand on the PCB but it is usually in the range of 10 to 470microF Larger values are required on PCBs with a large number of integrated circuits fast switching circuits and PSUs having long leads to the PCB

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics83

page 165

Decoupling Capacitor

During active device switching the high frequency switching noise created is distributed along the power supply lines The main function of the decoupling capacitor is to provide a localized source of DC power for the active devices thus reducing the switching noise propagating across the board and decoupling the noise to groundThe value of the decoupling capacitor is approximately 1100 to 11000 of the bypass capacitorIdeally the bypass and decoupling capacitors should be placed as close as possible to the power supply inlet to help filter high frequency noiseFor better EMC performance decoupling capacitors should placed as close as possible to each IC because track impedance will reduce the effectiveness of the decoupling function

page 166

Selection of Decoupling Capacitors

Three different capacitor values should be used to decouple both the high-voltage (such as 5V) and the low-voltage supplies (such as 18V) A good starting place is to use values of 10 μF one μF and 10 nF Approximately 30 10-nF caps are needed for the high frequency decoupling Only a few 1-μF and 10-μF caps are required for the low frequency decoupling Low Equivalent Series Resistance (ESR) and low Equivalent Series Inductance (ESL) capacitors should be used The above Table provides some example components available from AVX Similar capacitors are also available from other manufacturers such as Murata KEMET and Vishay

TAJE106K050R10microF06125C 104KAT 1W1microF03065C 103KAT 1W10nF

AVX Part NumberCapacitor Value

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics84

page 167

Vias for Decoupling Capacitors

Incorrect Correct

Capacitor Capacitor

Trace Vias

Solder Pads

page 168

Layout of Decoupling Capacitors

The basic strategy in this situation is to connect all the low-voltage power supply balls (VDDI and NVDDL) to the low-voltage power supply plane The plane is then decoupled by connecting the capacitors directly to the power and ground planes Start by placing as many capacitors directly opposite the MCU (on the other side of the PCB) between the vias from the center and outer rows of balls Place any remaining capacitors on the opposite side of the PCB as the MCU just outside the vias from the outer row of balls uniformly distributed around the MCU All VSS balls should be connected directly to the ground plane

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics85

page 169

Placement and Layout of Capacitors for High-Speed MCUs

Double-Sided Component Placement Application

Side View

Top ViewMPC55x

page 170

Placement and Layout of Capacitors for High-Speed MCUs

Single-Sided Component Placement Application

Side View

Top View

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics86

page 171

MPC56x Double-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane and 10 10-nF capacitors are used to decouple the power plane in their immediate vicinity

page 172

MPC56x Single-Sided Component Placement Application

The NVDDL and QVDDL balls should be connected directly to the power plane Place 10 10-nF capacitors as close as possible to the MCU (avoiding the corners where the VDD capacitors are located) The capacitors should be connected directly to the power and ground planes with many vias

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics87

page 173

PCB Layout Notes for Buck Converters

Power Electronics Lab NCTU Taiwan

電力電子晶片設計與DSP控制實驗室

Power Electronics IC amp DSP Control Lab國立交通大學 bull 電機與控制工程研究所

page 174

Example Buck converter

Primary loop current i1(t) contains large high frequency harmonicshence inductance of input loop is critical inductance causes ringing voltage spikes switching loss generation of B- and E- fields radiated EMI

Secondary loop contains a filter inductor and hence its current i2(t) is nearly dc

hence additional inductance is not a significant problem in the second loop

+minus i2(t)i1(t)

Q1

D1

i1(t)

i2(t)

Q1 D1

0

ILOAD

ILOAD

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics88

page 175

Bypass Capacitor

Parasitic inductances of input loop explicitly shown

Addition of bypass capacitor confines the pulsating current to a smallerloop

high frequency currents are shunted through capacitor instead of inputsource

+minus i1(t)

Q1

D1

+minus ig(t)

Q1

D1i1(t)

page 176

Reduce the Loop Area Especially the Critical Loop

Minimize area of the high frequency loop thereby minimizing itsinductance

+minus

Q1

D1

B fields nearly cancel

loop area Aci1

i1

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics89

page 177

Forward Converter

Two critical loops

Solution

+minus i2(t)i1(t)

+minus

page 178

Noise Coupling via Ground Loops

Unwanted coupling of signals via impedance of ground connections

All currents must flow in closed paths determine the entire loop in which large currents flow including the return connectionsGround (zero potential) references may not be the same for everyportion of the system

Stage 1 Stage 2 Stage 3+minus

+minus

Power supplies

+48 volts

+15 volts

inpu

t

outp

ut

inpu

t

outp

ut

inpu

t

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics90

page 179

Noise Coupling via Ground Loops

Example suppose the ground connections are

ldquoNoiserdquo from stages 2 and 3 couples into the input to stage 2This represents conducted EMI or specifically corruption of theground reference by system currents

Stage 1 Stage 2 Stage 3

+48 volts

+15 volts

+minus

+minus

i3i2

i2 + i3

i1(t)V ou

t1 Vout2

+ +

minus minus

( )3212 iiZVV goutin +minus=

page 180

Noise Coupling via Ground Loops

Example gate driver coupling via ground loop

+minus

+minus

ig(t)

Line input

+15 volt supply

analogcontrolchip

PWMcontrolchip

gatedriver

powerMOSFET

ig(t)

ConverterPowerstage

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics91

page 181

Noise Coupling via Ground Loops

Solution bypass capacitor and close coupling of gate and return leads

High frequency components of gate drive current are confined to a small loopA dc component of current is still drawn output of 15V supply and flows past the control chips Hence return conductor size must be sufficiently large

+minus

+minus

Line input

+15 volt supply

analogcontrol

chip

PWMcontrol

chipgate

driverpower

MOSFET

ConverterPowerstage

page 182

SPS Development of Advanced Microprocessors

Clock frequency changes in steps of 33MHzClock frequency changes in steps of 33MHzSupply voltage changes in steps of 25mV (depending on Supply voltage changes in steps of 25mV (depending on the voltage regulator)the voltage regulator)Supply voltage changes in every 5 msSupply voltage changes in every 5 ms

OnOn--chip decoupling capacitorchip decoupling capacitorOnOn--chip distributed power supplychip distributed power supplyPractical Soft Switching TechniquesPractical Soft Switching TechniquesDistributed MultiDistributed Multi--Phase DCPhase DC--DC ConveterDC ConveterNew Power Devices and Control ICs Need to be New Power Devices and Control ICs Need to be DevelopedDeveloped

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network

Powering Advanced Microprocessors

NCTU 2005 Course Notes SoC amp SoP for Power Electronics92

page 183

Conclusions

Development of low profile power convertersDevelopment of planar magnetic componentsStandard power modules will become dominantLow voltage power supply Redundant power supplyDistributed power supply systemDigital control and real-time networking for power controlSmart power converterDevelopment of renewable energy Energy network