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Energy-efficient PWM Controller with

Peak Power Excursion NCP1254/5

具备瞬时功率功能的高能效

PWM控制器NCP1254/5

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We have parts for

all of these

Topologies

forward flyback

half-bridge

push-pull

full-bridge

2-transistor forward

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Wide Portfolio of Controller Solutions

Output

Power

Relative

Performance

90W 150W 200W+

NCP1246 Fixed Freq. Flyback

NCP1380 Quasi Resonant Flyback

NCP1398 Resonant Half Bridge Controller

NCP1652A Flyback for single stage PFC

Incorporating PFC

Continuing to develop

higher performing

devices that reduce

cost and improve size

and efficiency

40W

NCP1250 6 pin Controller

4

AC-DC Fixed Frequency Flyback

Controller Evolution

2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 |

NCP1200

NCP1203

- w/o DSS

NCP1216

- Soft-Start

- Ramp Comp

NCP1217

- w/o DSS

1st Generation

High Voltage

Controllers

Fe

atu

res a

nd

Effic

ien

cy

3rd Generation

Major Leap in Light

Load Efficiency

4th Generation

Improved No Load

Power Consumption

NCP1237

-Dual OCP

-AC OVP

NCP1238

- No Dual OCP

NCP1288

- No Dss

NCP1236

-No Dual OCP

NCP1234

- w/o Brown Out

NCP1250

-No HV

NCP1251

-Vcc OVP

2nd Generation

Advance Protection

Features

NCP1230 - PFC Stby

Industry first AC-DC

controllers with Direct

Connection to High

Voltage Line

-Timer Based Over Current

Protection

-Latch Fault Protection

-Frequency Foldback

-Brown Out Protection

-Overpower Compensation

-X2 Capacitor Discharge

-Low Consumption Off

Mode

NCP1246

NCP1244

- w/o Brown Out

NCP1219

NCP1271

- w/o DSS

NCP4354 - No Load

Detection

Dynamic Self Supply –

No need for Auxiliary

Winding

Introduction of Skip Mode

NCP1247 NCP1249

NCP1255

- Peak Power

NCP1254

-No BO

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Low Standby Product Roadmap N

o L

oa

d S

tan

db

y P

ow

er

NCP1246/47 • Active X2 Discharge

• Off Mode

| 2011 | 2012 | 2013

NCP4354 • No Load

Detection

< 30 mW (230Vac)

< 10 mW (230Vac)

< 5 mW (230Vac)

NCP1937 • Active X2 Discharge

• Improved Off Mode

NCP4355 • No Load

Detection

NCP1249 • Active X2 Discharge

• Off Mode

• Improved ICC

NCP4354 • No Load

Detection

NCP4352 • ECO Mode

NCP1250/1/3 • Low Icc, Low Istart

NCP124x • Improved ICC

• Improved BO Divider

NCP4355 • No Load

Detection

NCP1249 • Active X2 Discharge

• Off Mode

• Improved ICC

NCP431 •Standard

NCP1254/5 • Peak Power

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NCP1255 Fixed Frequency PWM Controller

with Peak Power Excursion

The NCP1255 is a fixed frequency, PWM controller designed for applications requiring a peak power capability. It

includes frequency foldback and skip cycle to ensures a high efficiency design across the entire load range.

• 65 kHz frequency with

130kHz during peak power

• Frequency Foldback with

Skip Mode

• Adjustable Brown Out

Protection

• Adjustable dual timer OCP

• Vcc OVP

• Peak power capability

without large transformer

• Improved light-load

efficiency

• Improved protection

• Adjustable Over Power Protection

• Frequency Jittering in normal and frequency foldback

• Internal 4 ms soft-start

• Low no-load standby power

• Double Vcc hiccup for reduced power in fault

• Printer power supplies

• AC-DC Adapters

• Game console adapters

Market & Applications

Other Features

Ordering & Package Information

Part Number Frequency OCP

NCP1255AD65R2G 65 kHz Latched

NCP1255BD65R2G 65 kHz Auto-Recovery

Eris

Vbulk

..

ramp

comp.

OPP

Vout

OVP

.

1

2

3

4 5

8

6

7

Eris

BO

Benefits

Value Proposition

Unique Features

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• Fixed frequency peak-current mode control

• Frequency foldback down to 26 kHz in light load conditions

• Frequency jittering from full load to skip-cycle

• Skip-cycle operation in no-load conditions

• Adjustable slope compensation for Continuous Conduction Mode

• Non-dissipative proprietary OPP compensation

• Latch input for OVP and OTP implementations

• 15-µA maximum start-up current

• 4-ms internal soft-start sequence

• Adjustable timer-based short-circuit protection

• Auto-recovery or Latched

• 130 kHz frequency excursion for peak power requirements

• Adjustable Brown Out Protection

• Vcc supply up to 35 V

• 100% to 25% timer reduction from overload to short-circuit fault

• Double Vcc hiccup for reduced average power in fault mode

Feature Overview

Upgraded

Features

8

Eris

Vbulk

..

ramp

comp.

OPP

Vout

OVP

.

1

2

3

4 5

8

6

7

Eris

BO

NCP1255 Typical Schematic

OPP /

Latch

FB

CS

GND

Timer

Vcc

DRV

9

Peak Power Excursion

Many power supplies now have requirements for both nominal power

and peak power. For example, 60W nominal with 90W peak.

The peak power is only required in short bursts. Rather than design the

power supply for 90W continuous power, we can use advanced control

techniques to meet these requirements.

These controllers increase the switching frequency for a short duration

(<1s) while keeping the peak current at a fixed value.

This allows for increased power delivery without increasing the size of the

transformer, lowering costs and minimizing form factor!

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2out p peak swP L I F

@130kHz 2 @65kHzout outP P

65 kHz

130 kHz

nominal

peak

x2

*For DCM Operation

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NCP1255 Peak Power Excursion

When feedback voltage increases above 3.2V, the switching frequency

increases until it doubles at VFB=4.0V. Peak current remains frozen.

This allows the SMPS to deliver more power without growing transformer

size

Fsw

VFB

VCS

VFB

65 kHz

26 kHz

400 mVVfold

3.2 V Vfold 3.2 V

0.8 V

0.47 V

FB

Vfreeze

0.25 V

1 V 1.9 V

1.9 V

max

min

max

min

Vfold,end

Frequency Peak current setpoint

130 kHz

4 V Vskip

0.4 V

1.5 V

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Overload Timer for Peak Power

The peak power duration is limited by the overload timer

The nominal overload timer is adjustable (up to 1 second)

There are dual levels for the overload timer, dependent of the FB voltage

The timer is divided by 4 when a short circuit is detected

VFB (V)

t

4.0

3.2

Open loop voltage

100% timer – overload

25% timer – short-circuit

65 kHz

130 kHz

Fixed-frequency variable peak current

26 kHz

Max Ipeak

31% max Ipeak

Skip cycle0.4

1

4.5 max

1.91.5 Frequency foldback variable peak current

65 kHz

Frozen peak current

Frozen current Fixed frequency variable peak current

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Dual Level Overload / Short Circuit

When 3.2 V < VFB < 4.0 V, an overload condition is detected

When VFB > 4.0 V, a short circuit is detected and the fault timer is decreased

to 25%

* Actual OVL/SC thresholds are lower when using OPP. For example, with an

OPP level of -200 mV, the OVL threshold becomes (0.8 – 0.2) x 4 = 2.4 V

VFB

4.0 V

3.2 V

VFB

4.0 V

3.2 V

fault fault

VCt

OVLSC

SCOVLSCOVL

130 kHz

65 kHz

130 kHz

65 kHz

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Brown Out Protection

A simple comparator monitors the input voltage on the BO pin. When line

voltage is too low, pulses are stopped and the Vcc hiccups

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Brown Out Design Equations

The hysteresis is fixed by the internal ratio VBOon/VBOoff = 1.33

Select the bridge current. Say 10 µA. Then R2 is:

2

0.880kΩ

10

BOon

bridge

VR

I u

,

1

1100.8

3.14 3.4MΩ10

in onBOon

bridge

VV

RI u

The turn-off voltage will then be:

7758Vrms

1.33 1.33

BOonBOoff

VV

Turn-on

is 77 V

rms

2R

1R

BO

Half-wave

rectification

1μF

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Brown Out Protection

The Brown Out recovery is always synchronized with the Vcc signal

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Double Vcc Hiccup

During a fault, driving pulses are stopped and Vcc drops to Vcc(min)

At Vcc(min) the controller consumption drops to a few uA and the Vcc recharges by

the resistive staring network

When Vcc reaches Vcc(on) the controller purposely ignores the re-start and waits for

another Vcc cycle

This lowers the duty ratio, reducing average input power during fault conditions

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Double Vcc Hiccup w/ Brown Out

If a Brown Out transition is detected, the double hiccup is interrupted and

the controller re-starts at the next Vcc(on) in order to shorten the re-start

time

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NCP1254 Fixed Frequency PWM Controller

with Peak Power Excursion in tiny TSOP-6

The NCP1254 is a fixed frequency, PWM controller in TSOP-6 designed for applications requiring a peak power

capability. It includes frequency foldback and skip cycle to ensures a high efficiency design across the entire load range.

• 65 kHz frequency with

130kHz during peak power

• Frequency Foldback with

Skip Mode

• Adjustable Over Power

Protection

• Fixed dual timer OCP

• Peak power capability

without large transformer

• Improved light-load

efficiency

• Improved protection

• Vcc OVP

• Frequency Jittering in normal and frequency foldback

• Internal 4 ms soft-start

• Low no-load standby power

• Double Vcc hiccup for reduced power in fault

• Printer power supplies

• AC-DC Adapters

• Game console adapters

Market & Applications

Other Features

Ordering & Package Information

Part Number Frequency OCP

NCP1254ASN65T1G 65 kHz Latched

NCP1254BSN65T1G 65 kHz Auto-Recovery

1

2

3

6

4

5

NCP125x

Vbulk

..

rampcomp.

OPP

Vout

OVP

.

Value Propositions

Unique Features Benefits

19

NCP1254 Typical Schematic

OPP /

Latch

FB

CS

GND

Vcc

DRV 1

2

3

6

4

5

NCP125x

Vbulk

..

rampcomp.

OPP

Vout

OVP

.

NCP1254

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NCP1254 vs NCP1255 Feature Comparison

NCP1254 NCP1255

Fault Timer 200ms Fixed Adjustable

Brown Out No Yes

Device Options Latch (A version)

Auto-Recovery (B version)

Latch (A version)

Auto-Recovery (B version)

Package TSOP-6 SOIC-8

Operating Frequency 65kHz->130kHz 65kHz->130kHz

1

2

3

4 5

8

6

7

DRV

Vcc

BO

Gnd

CS

FB

OPP

Latch Timer

NC

P1

25

5 1

2

3

6

4

5

OPP/Latch

FB

CS

GND DRV

Vcc

NC

P1

25

4

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Demoboard

• Vin = 100 – 240 Vrms, Vout = 32 V

• Pout = 25W nominal, 41W peak

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Demoboard Efficiency

WoutP

%

100VrmsinV

230VrmsinV

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Peak Power Performance

outv t

100 V rmsinV FBv t

,

0.5 A

1.1A

out

out peak

I

I

outv t

100 V rmsinV FBv t

1.15

3.5%

V

,

0.5 A

1.3 A

out

out peak

I

I

Overload Region - 35W for 100ms Short Region - 41W for <50ms