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中小型面板之电源管理器件及应用介绍

郑刚 专案副理 http://www.richtek.com

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OutlineOutline

LDO Linear Regulators for Mobile Phone Application

LED Drivers for Display Backlighting

PCB Layout Considerations for Mobile Phone Power Circuit

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LDO Linear Regulators for Mobile Phone Application

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Outline Outline

Fundamental Introduction of LDO

Important Characteristic of LDO

Richtek LDOs for Cellular Phone Applications

LDO Topologies

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Low Drop Out: A linear voltage regulator that will operate even when the input voltage barely exceeds the desired output voltage.

Applications: Cellular Phones Notebook PCMCIA Cards Mother Board Power Supply Cable Modems Wireless LAN ……………………

Fundamental Introduction of LDOFundamental Introduction of LDOWhat is LDO ?

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I-V Characteristic of N-channel MOSFETI-V Characteristic of N-channel MOSFET

VIN

RLOAD

ControlCircuit

+ VDS -

D S

GR1

R2

NMOSSlop=1/Ri

Cutoff Region : VGS < Vt

Linear Region : VDS < VGS-Vt

Saturation Region: VDS > VGS-Vt

Vds=VIN - Vo

+

Vo

-

2

2

1DSoxnDS vCi Boundary:

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LDO TopologiesLDO Topologies

1. The reference

2. The pass element

3. The sampling resistor

4. The error amplifier

Four basic functional blocks:

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Load RegulationLoad Regulation Load regulation is a measure of the circuit’s ability to maintain the specified output voltage under varying load conditions.

Load regulation is defined as:

O

O

I

VregulationLoad

RT9182

Vo

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Line regulation is a measure of the circuit’s ability to maintain the specified output voltage with varying input voltage.

Line regulation is defined as:

Line RegulationLine Regulation

I

O

V

VregulationLine

RT9182

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Transient ResponseTransient ResponseThe transient response is an important specification, which is the maximum allowable output voltage variation for a load current step change.

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PSRR (Power Supply Rejection Ratio)PSRR (Power Supply Rejection Ratio)This specification is the measure of how well the regulator rejects an AC signal riding on a nominal input DC voltage

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Improved PSRRImproved PSRR

LC filter An additional linear regulator

One or more cascades of external RC filters

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Output Noise VoltageOutput Noise VoltageOutput noise voltage is the RMS output noise voltage over a bandwidth (10Hz to 100KHz) under the conditions of a constant output current and a ripple-free input voltage. The noise generated only by the LDO itself.

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The LDO output noise can be reduced by effective LDO internal design and external bypass and compensation

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Thermal ResistanceThermal Resistance

QDOI PPPP OID PPP

JAAJD TTP /)(

DAJJA PTT /)(

max DD PP or max JAJA Back

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VI-max= 4.2V

Design ExampleDesign Example

Vo= 2.5V

1. 100mA duty cycle D1 = 0.378/4.61=8.2%; 60mA duty cycle D2=91.8%

2. PD(100mA) = (Vi-Vo)Io+(Vi x Iq)

= (4.2V-2.5V)100mA + (4.2V x 130uA) = 170.55mW

PD(60mA) = (4.2V-2.5V)60mA + (4.2 x 130uA)= 102.55mW

3. PD(total) = PD(100mA) x D1 + PD(60mA) x D2 = 170.55mW x 8.2% +

102.55mW x 91.8% =108.13 mW

The maximum power dissipation for RT9198 operating at an ambient temperature of 70 : SOT-25: 220mW, SC-70: 165mW

Selecting SC-70 package

ILoa

d (m

A) 100mA

T(ms)

60mA

4.61ms

0.378ms

A 2.5V system using RT9198 to supply

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CMOS Camera Module PowerCMOS Camera Module Power

CIF

Array Size 640X480 ( VGA )

Digital 2.5VDC ± 10%

Analog 2.5VDC ± 4%

DOVDD is 2.8~3.0V sensor digital IO power

Dropout is not critical. ( Li-ion battery range from 3.2V to 4.2V) Require low-noise and high PSRR LDOs for AVDD. This LDO is not on all the time, so the quiescent current is not care. Small package.

VDD

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RT9167/A Low-Noise, 300mA/500mA LDO Regulator Feature Shutdown function Low-Dropout: 350mV at 300mA Low Noise Output Short circuit and thermal protection function SOT-25 package

RT9178 Ultra Low Noise, High PSRR LDO Regulator Feature 50uV Ultra-Low Output Noise Quick Start-up ( Typical 100us) Low-Dropout: 200mV at 200mA High PSRR SOT-25 package

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RT9182 Dual, Low-Noise, 200mA LDO Regulator Feature Dual shutdown pin control each output Low-Dropout: 120mV at 100mA 124uVrms Low Noise Output Short circuit and thermal protection function SOT-26 package

RT9198 300mA, High PSRR LDO Regulator Feature <0.01uA quiescent current when shutdown Low-Dropout: 220mV at 300mA High PSRR and ultra-low-noise for phone application SOT25/SC-70 package

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LED Drivers for Display Backlighting

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Outline

Features of White LEDFeatures of White LED Driver Solutions for WLEDDriver Solutions for WLED Efficiency AnalysisEfficiency Analysis RichTek Solutions for WLED DriverRichTek Solutions for WLED Driver

Backlight Driver Solutions for Dual PanelsBacklight Driver Solutions for Dual Panels

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White LED Background Info

Brightness is proportional to CURRENT Most popular LED currents (ILED) for backlight:10~15mA

(for camera flash: 50~120mA) LED forward voltage (VLED): Can range from 3V to 4Vtypically. Most

common: 3.3V~3.6V Forward voltage is a measure of efficiency of the LED… does not affect

brightness much

The LED with the higher VLED for a given current burns more power (VxI)

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White LED Connection

Parallel Connection No inductor requirement Low EMI

Series Connection Lighting uniformity Higher efficiency Higher current capability Easy layout

EXTVDD

CE

WLED Driver

GND

Charge Pump Topology

Panel

LXVDD

CE

WLED Driver FB

GND

Boost Topology

Panel

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WLED Driver Solution for Backlight

LX

VDD

CE

Boost FB

GND

Boost Topology RT9271

Panel

Charge Pump with RT9362Current source Topology RT9360

VDD

CE

Panel

CP

CS

VDD

CE

CS

Current source Topology RT9300

Panel

Low VF LED

VDD

CE

CP

Charge Pump Topology RT9361

Panel

Same VF LED

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WLED Driver Solution - Boost Converter

CS R

+

Vo

-V s

L

+ V L -

D IoLI

CCMCCM SS on , 0 on , 0 ＜＜ tt ＜＜ ttonon

CV s

L

R

+ V L - +

-

IL

Vo

SS off , t off , tonon ＜＜ tt ＜＜ ttoffoff

C

L

R

+ V L - +

Vo

-

IL

V s

From volt-second balance principle

so

os

sos

VD

V

TVDTV

TDVVDTV

1

1

)1(

)1)((

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WLED Driver Solution - Boost Converter

S

)(tiL

Ia

Ib 2

baL

III

DT (1-D)T

T

)(tVL

Vs-Vo

Vs

ton toff

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WLED Driver Solution - Boost Converter

DCMDCM

SS on , 0 on , 0 ＜＜ tt ＜＜ t1t1

SS off , t1 off , t1 ＜＜ tt ＜＜ t2t2

SS off , off , D offD off, t2, t2 ＜＜ tt ＜＜ TT

CV s

L

R

+ V L - +

Vo

-

IL

CV s

L

R

+ V L - +

-

IL

Vo

C

L

R

+ V L - +

Vo

-

IL

V s

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WLED Driver Solution - Boost Converter

S

)(tiL

Ib

T

)(tVL

Vs-Vo

Vs

t1 t2 t3

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WLED Driver Solution - Charge PumpOn StateOn State

Off StateOff State

During the on state, Q1 and Q4 are closed, which charge C1 to VIN

During the off state, Q3 and Q2 are closed.The output voltage is VIN plus VC1, that is 2VIN

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LED Driver Efficiency vs. Converter Efficiency

LED Driver Efficiency LED Driver Efficiency

= “Power delivered to the LEDs” ÷ “Power drawn by the Input”= “Power delivered to the LEDs” ÷ “Power drawn by the Input”

LED Driver LED Driver Efficiency = PLED ÷ PIN = (NxVLEDxILED) ÷ (VINxIIN)

Converter EfficiencyConverter Efficiency

= “Power delivered to the Output pin” ÷ “Power drawn by the Input”= “Power delivered to the Output pin” ÷ “Power drawn by the Input”

Converter Efficiency= POUT ÷ PIN = (VOUTxIOUT) ÷ (VINxIIN)

Converter Efficiency does not account for Power losses of external ballast resistors

LED Driver Efficiency & Converter Efficiency confusion can always be avoided by comparing “INPUT POWER”

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Efficiency - Example

Parallel Connection – Charge Parallel Connection – Charge PumpPump

LED Power (PLED)

= VF * IOUT * 3

= 3.5 * 20mA * 3

= 210mW

Input Power (PIN)

= VOUT * IOUT / Converter

Efficiency = 5V * 20mA * 3 / 0.85 = 352.9mW

LED Driver Efficiency

= PLED / PIN

= 59.5%

Series Connection – BoostSeries Connection – Boost

LED Power (PLED)

= VF * 3 * IOUT

= 3.5 * 3 * 20mA = 210mW

Input Power (PIN)

= VOUT * IOUT / Converter

Efficiency = (3.5 * 3 + 0.25)V * 20mA / 0.85 = 252.9mW

LED Driver Efficiency

= PLED / PIN

= 83% AssumptionAssumption

Test Condition is in 3 WLEDs – Mobile phone application Forward voltage of WLED is 3.5V and output current is 20mA The converter efficiency of boost and charge pump is the same as

85% The output of charge pump is about 5V The feedback of boost is 0.25V

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WLED Driver Solution - Charge Pump

The amount of charge flowing into C1 during on state is equal to that flowing out of C1 at off state

The efficiency of charge pump is given below:

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LCM Power Solution

White LED DriverWhite LED Driver Single PanelSingle Panel

- RT9271 (Boost DC/DC Converter)

- RT9360 (Charge Pump + Current Source)

- RT9362 (Charge Pump + Current Source)

- RT9361 (Charge Pump)

- RT9300 (Current Source)

Dual PanelDual Panel

- RT9272 (TFT/CSTN + TFT/CSTN)

- RT9273 (TFT/CSTN + OLED)

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Power Solution

RT9271White LED Boost converter with OVP

Feature High Efficiency: 85% typical 20V Internal Switch Fast 1.1MHz Switching Frequency Requires Only 1uF Input/Output Capacitor Low FB Voltage - 0.25V Optional 15V Over Voltage Protection Support camera flash application Low Profile SOT-25/26 Package Typical Application

Up to 80mA peak

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Power Solution

RT9271White LED Boost converter with OVP

Function Block Diagram

VDD

CE

OVP

FB

CE

GND

VCC

LX

Panel

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Power Solution

RT9271White LED Boost converter with OVP

Dimming Control

RT9271RT9271 FBFB

Using a DC VoltageUsing a DC Voltage

Using a Logic SignalUsing a Logic Signal

Using a Filtered PWM ControlUsing a Filtered PWM Control

RT9271RT9271 FBFB

RT9271RT9271 FBFB

200~1KHz

RT9271RT9271CECE FBFB

Using a PWM ControlUsing a PWM Control

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Power Solution

Inductor Selection

Inductance valueInductance value ESR: copper lossESR: copper loss Magnetic loss Magnetic loss SaturationSaturation Current RatingCurrent Rating Operation Operation

frequencyfrequency Leakage & NoiseLeakage & Noise HeightHeight

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Power Solution

RT9360High Efficiency Charge Pump WLED Driver

Feature Peak efficiency over 92% Current Regulation for up to 4WLEDs Digital 3 bit output control logic Soft-start, short circuit protection function Three charge pump modes of operation Support camera flash application QFN-4x4 package

Typical Application

Up to 200mA peak

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Power Solution

RT9362High Efficiency Charge Pump WLED Driver

Feature Everything is the same as RT9360 But has smaller size and different pin definition

QFN-3x3 package

Typical Application

Up to 200mA peak

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Power Solution

RT9360High Efficiency Charge Pump WLED Driver

Function Block Diagram

EN

VDD

Panel

Control Inputs

EN

GND

VIN VOUT

CTRL0CTRL1CTRL2

LED1LED2LED3LED4

ISET

C2P C2NC1P C1N

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Power Solution

RT9360High Efficiency Charge Pump WLED Driver

Efficiency

RT9360 (1x, 1.5x 2x CP+CS)Efficiency: 85%~95%

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Power Solution

RT9360High Efficiency Charge Pump WLED Driver

Dimming Control

Using a DC VoltageUsing a DC Voltage Using a PWM ControlUsing a PWM Control

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Power Solution

RT9360High Efficiency Charge Pump WLED Driver

Dimming Control

Using a Logic SignalUsing a Logic SignalBack

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White LED for Backlight

RT9361120mA, Regulated Charge Pump

Feature Useful for Same VF WLED Application ( VF difference < 0.1V) Step Up type Voltage Converter 1Mhz Frequency Operation Allows Small Capacitor Short Circuit and Over Temperature Protection Tiny Small Package SOT-26

VOUTVDD

GNDCECIN

COUT

C+ C-

Ccp

VOUT= 5VVIN= 2.8~4.5V

2.2uF2.2uF

0.22uF/

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White LED for Backlight

RT930080mA, Current Regulator

Feature Useful for Low VF WLED Application No External Components Very Low Internal Dropout Voltage(60mV) Initial Current Sink 20mA/15mA Tiny Small Package SOT-26 PWM Dimming Control

VMBAT

GNDCE

LED1 LED2 LED3 LED4

PWM

NoNoExternalExternalComponentsComponents!!

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Dual Panel Solution

CSTN/TFT + CSTN/TFT

CSTN/TFT + OLED

Dual Channel Dual Channel powerspowers

Main and Sub-DisplaysMain and Sub-Displays

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Power Solution

RT9272Constant Current WLED Driver for Dual Panel Mobile Phone

Feature Low Vin operating range: 2.4~6V Maximum output voltage up to 16V 1.4MHz Switching Frequency Share one set of inductor and Schottky diode for 2 channel Complete protection: OVP, OCP, OTP and SS

DFN3x3-10 PackageTypical Application

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Power Solution

RT9273OLED + WLED Driver for Dual Panel Mobile Phone

Feature Low Vin operating range: 2.7~4.5V Maximum output voltage up to 16V 1.1MHz Switching Frequency Share one set of inductor and Schottky diode for 2 channel Complete protection: OVP, OCP, OTP and SS

DFN3x3-10 PackageTypical Application

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PCB Layout Considerations for Mobile Phone Power Circuit

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OutlinesOutlines

Routing the DC/DC Converter Power StageRouting the DC/DC Converter Power Stage

Other Considerations Other Considerations

IntroductionIntroduction

The Right Connection of IC ControllerThe Right Connection of IC Controller

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Because of rapid charges in voltages and currents (dV/dt, di/dt)

within a switching converter, switching power supply is a

source of EMI.

IntroductionIntroduction

EMI Source

Equipment or device affected by

EMIConducted

radiated

• Conduction Propagation

• Space Conduction (Radiation)

• Capacitive Coupling (E field)

• Inductive Coupling (B field)

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A

V

t

T

tr

H

trf

2AH/T

f1 f2

-20dB/dec

-40dB/dec

Reduction of EMIReduction of EMI

EMI Filter

Consideration of driver design.

Using Snubber-circuit

Using soft-switching technology.

Proper PCB layout of power circuit

1/πH 1/πtr

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Boost ConverterBoost Converter

Vin

I o Lv + - v D +-

L F

i S

i L

V o

+

-

i D

S v S

+

- C F

i in

R L

D OFF ON ON

S

v D

i L

v S

I o

i D

T on T off

Vin / LF slopes

- (V -V ) o / LF

I in

V o

OFF

in

V o

VL

Vin

Vo-Vin

DV

VM

in

o

1

1

CCM

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Model of Boost Converter LayoutModel of Boost Converter Layout

L= LfT + LfD + LfC

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RT9271 PCB LayoutRT9271 PCB Layout

CinLDiodeCout : trace as short and thick as possible

L RT9271’s Lx pinRT9271’s GND pin : trace as short and thick as possible.

The through hole of RT9271’s GND pin as large and many as possible

The Inductor is far away receiver and microphone The voice trace is far away RT9271 The embedded antenna is far away and different side

RT9271 R2 as close as RT9271 Reduce Cout value or use VDC brightness control to

avoid audio noise Higher PWM frequency to avoid the flicker of LCM.

VCC

EN

GND

LX

FB

RT9271CE

DimmingControl

C11uF

C21uF

D1SS0520

L110uH

R212

OVP

D2

D5

D4

D3

Vin2.4 to 6V

Grounding

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Example layout for Buck Converter power stage

Any PCB trace can act as an antenna. To cancel radiated fields, take care to minimize the area of the AC current loop

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Grounds are important

Control Ground is the ground connected to the control IC and all

of its associated passive components. This ground is extremely

sensitive. Place it only after the other AC current loops are placed.

The Right Connection of IC ControllerThe Right Connection of IC Controller

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Connections of IC ControllerConnections of IC Controller

(a). Improper connection of Vcc.

Cause the voltage bounce on Vcc.

(b). Proper connection of Vcc.

dt

tdiLtVL

)()(

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Routing of Capacitor TracesRouting of Capacitor Traces

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Voltage DividerVoltage Divider

The path from resistor divider to error amplifier should be as short as possible and consists of parallel paths to reduce noise pick-up.

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LDO PCB LayoutLDO PCB Layout

Recommended LDO Regulator Layout

Common LDO Regulator Layout

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LED

4

LED

3

EN

LED

1

LED

2

CTRL2

CTRL1

CTRL0

GND

C2+

C2N

C1N

C1+ VIN

VO

UT

ISE

T

RT9360

1

2

3

4

5678

9

10

11

12

13 14 15 16

VIN

C1

1uF

C2

1uF

COUT

1uF

RSET

VADJRADJ

The Charge Pump is a high-frequency switched-capacitor voltage regulator. For best circuit performance, use a solid ground plane and place CIN and COUT as close to the IC as possible.

Charge Pump PCB LayoutCharge Pump PCB Layout

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Other Considerations Other Considerations Reduce RF EMI Issue

Keep HF and RF tracks as short as possible

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Avoid track stubs, these cause reflection and harmonics

On sensitive components and terminations use surrounding guard ring and ground fill where possible

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System Board

Avoid noise coupling

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The Copper Loss of PCBThe Copper Loss of PCB

The resistance of one square mm of PCB trace is 0.5~0.6 mΩ.(1 oz thickness)

From experience, 1mm width can stand 0.5A DC current. (1 oz thickness) (J=14.3A/mm2)

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Taiwan TOP 1 Power Management Solution ProviderTaiwan TOP 1 Power Management Solution Provider

Strongly Technical SupportStrongly Technical Support

Fast Delivery TimeFast Delivery Time

Aggressive BOM CostAggressive BOM Cost

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