AC-DC LCD TV Power Architecture and

LED Backlight

LCD TV Power Architecture and LED Backlight• LCD-TV Market

– Power Reduction Trend – Edge LED LCD TV Backlight

• 26” to 42” H-V LIPS Reference Design

• 46/47” Power Reference (PSU) for any Backlight solution– Interleaved Frequency Clamp CrM PFC with NCP1631– Quasi Resonance Valley lock out Flyback Converter with NCP1379– ECO Standby SMPS Solution with NCP1053A

• 46/47” Backlight solution– LIPS Inverter– Edge LED Driver

• Conclusion

LCD-TV Shipments by Size

Source: Displaysearch 2Q 09

Power Reduction Trend• Regulatory reduce power

consumption in active and standby mode

• New technologies focused on improving efficiency

Source: Sharp

• Proposed ENERGYSTAR TV regulations (V4.0) will lower average power targets

Power consumption reduction ~ - 50% over 2 years

Proposed ENERGY STAR rev4.0 Standards

Target Effective Date: May 2010

Very few LCD-TV passproposed new standard,most are Samsung LED

LCD-TV LED Backlighting

LED TVs is forecast to grow to 20-32% (~64 M#) by 2012

Source: DisplaySearch July 2009

Comparison of LED LCD TV Backlight Options

• Thermal limitations• High system cost due to number

of LEDs and # of Drivers• Picture artifacts

• System Noise & EMI• Using lots of external components

(Inductor, capacitor, diode)Concerns

Boost or Buck plus Multi-channel linear

High voltage Boost, buck, linear with Vf adjustment

LED driver

Direct-type LED BLUEdge-lit LED BLU

Merit

• Deep blacks, better contrast • Local dimming • Scanning for higher frame rate• Low power consumption• Complex signal processing

• High Power Efficiency• Good system reliability independent

LEDs performance.• Cost down of system• Slim LCD TV

Edge LED > 90% ?

Power Architectures Remain Varied

PFCCRM

Interleave FCCrMCCM

70 - 400+ W

Signal PowerFlyback

Resonant HB30 – 80 W

Backlight PowerFlyback / Resonant HB

24V / 150V+ for LEDHV-LIPS for CCFL / EEFL

50 – 300 W

Traditional 24 V Backlight and HV-LIPS approachThin TV design impacts solutions choices as well

ECO Standby< 5 W

32” HV-LIPS Reference Design• For 32” (highest volume size) with possible extension to 26/42”

– Available since March 2009– For CCFL ( >> 95% of backlight) with possible extension to EEFL– Single PCB with LCD and Inverter Power Supply

• Very Cost effective solution– No extra Standby SMPS– Straightforward CrM PFC

• Key ON Semiconductor ICs– NCP1607 as CrM PFC controller– NCP1351 or NCP1219 as Flyback with low power standby mode

• LX6503 Microsemi Backlight controller– Full Bridge High Voltage Inverter without High Side Driver (discrete circuit)– Jin balance solution

32” HV-LIPS LCD TV Block Diagram

HV-LIPS LCD TV Complete Solution

Green Point Reference design documentation:http://www.ONSemiconductor.com/pub_link/Collateral/TND3

60-D.PDF

12 CCFL175 mm x 330 mm x 25 mmAll-in-one board with current balancer

46/47” Power Reference (PSU)

•Higher power LCD-TVs from 40/42” to 52”/55”

•Project focusing on power stage only– ECO standby “OFF mode”– Interleaved frequency clamp CrM PFC – Up to 70 W Flyback – Up to 200 W for backlight

•Low profile design– 1st phase: < 13 mm – 2nd phase: < 8 mm

46” LCD TV Power Block Diagram

46” LCD TV Power Solution Unit (PSU)

Low Profile design < 13 mm / 17.5 mm total

46” LCD TV PFC Solution

•Up to 300 W Interleaved Frequency Clamp CrMPFC– Better EMI and EMC – Lower Irms for output C– Better for SLIM design– Standard parts (= 32”CrM)

•New controller NCP1631

•Easy SLIM narrow range version

Interleaved FCCrM PFC for > 200 W & SLIM design

PFC Summary

46” LCD TV PFC Schematic

ZCD1_1

ZCD1_10

POWER_BOOSTBO_PFC

R3

0.065 2 W 5%

C13

680n

F1FUSE 6A-250V

R23 150K

Q5

BC856ALT13

1

2

R39 NA

Q6

BC856ALT1 3

1

2

R41270K

R4310K

R11 1K

+C6

68u 450V

*

*

ncL2200uH

85

211

6 7

9

R3024K

D3

MUR550APF

C5 X2 100nF 275V

C10NA

R18 150K

L NFGFG FG

CN0014333-W05ST

Q4BC808-25LT1

3

1

2

R3410K

LINE_NEUTRAL

Q3BC808-25LT1

3

1

2

CN0034324-07S

12345678

RV5

TVR10471KSY

R3610k

R3120K

R11M

1 2

34

L4 8.7mH

CFS28

R41M

CN401Gnd_Lug

1

RT1 NTC 2R5

R262K2

R101M

J106 INSTALL

1 2

R2747k

D5 MMSD4148

C18220p

D6 MMSD4148

C11NA

R17 150K

SW1

RELAY SPST

43

1 2

C21

220n

D11 1N4007

R3339K

*

*

L3200uH

41

76

2 3

910

D2 MUR550APF

R281M

BacklightInputPower andSignal

R19 150K

+C253.3 uF 400V

R350

C20.47uF

450VC3

Y 1nF

90-264_VAC_INPUT

F2 4R7 1W

C4

Y 1nF

+-

BD1

GBU806

4

2

1

3

C10.47uF450V

C22

NA

Q2 STP9NK50ZFP

3

1

2

C12 X2 1uF 275V

L1 50uH

R6

47

R16 22K

R371K

R241K5

R81M

R21 150K

PC001ASFH817A

21

R7

47

R22 150K

C15

100n

R201M

IC1 NCP1631

ZCD21

FB2

Rt3

OSC4

Vcontrol5

Freq-Fall Back6

BO7

OVP/UVP8

CS9

Latch OFF10

DRV211

Vcc 12GND

13DRV1

14PFC-OK

15ZCD1

16

R91M

R29120K

R151M

D8 MMSD4148

R12 1K

C710nF 500V

R21M

+

C16

10u 50V

R14 22K

R51M

D1 1N5406

1 2

34

L5 8.7mH

CFS28

C20

10n

R131M

R2515K

R381K

R4210K

C19

220n

+C243.3 uF 400V

+C8

68u 450V

C17

1nF

Q1 STP9NK50ZFP

3

1

2

PFC_OUT

VCC4PFC-OK

Standby_supply

PFC_OUT

FB_PFC

O_UVP

FB_PFCO_UVP

RELAY2RELAY1

L3Q2

L2Q1

46” LCD TV QR Flyback Solution•Flyback converter

– Up to 70 W max – Up to 3 output with 4 A Max

•Quasi Resonance Flyback Converter– Reduced EMI – Best safety behaviors

•New NCP1379 controller– Valley-lockout system – Variable frequency mode for ultra low power mode – Over current protection with auto recovery internal

timer

46” LCD TV PWM Fixed F Flyback Solution

•PWM Fixed Frequency Flyback converter– 50 kHz Fixed frequency – Allow natural CCM

•New NCP1252 controller– Adjustable switching frequency with skip mode – Adjustable soft start– Over current protection with internal timer

•Alternative solution to previous QR mode– Both designs

• on the same PCB • with the same switching frequency• with the same key parts

QR Valley lock-out or PWM Flyback SMPS up to 70 W

46” LCD TV Flyback Schematic

2_5VREF

D207

MBRF20L80CTGto220

1 2

3

Flyback power toSignal processingand Audio board

R228 1K

Backlightcontrollersupply toBacklightboard

D215

MMSD4148

R23810K

R203 33k

R2210.47R 2W CN403

Gnd_Lug

1

+C206

470u 16V

PN

D216

MMSD4148

PC101B

SFH817A

43

CN2024324-03S

123

R2121K

L201 10uH1 2

+C219

470u 16V

PN R219

2K2

+C216

10u 50V

+C209

470u 16V

PN

L202 10uH1 2

R209 100

R231 16K2

+C207

470u 16V

PN

*

**

*

*

T200750875731

3

7

1

5

612

11

8

109

R2231K

R226 1K

C218100p 1KV

D206MMSD4148

C212

220p C215

100n

D203

MMSD4148 NCP1379IC200

VCC 6

ZCD1

CT8

FB2

DRV 5GND4

CS3

BO7

R255

10M 2W

R2422K2

D205

BAV21

C225

Y 1nF

+C205

470u 16V

PN

D211MMSD4148

R22047k

R21410k

R2051K

ZD200MMSZ15T1

+C221

470u 16V

PN

Q201BC858ALT1

3

1

2

D209

MMSD4148R218

3K3

Q207BC858ALT1

3

1

2

+C224470u 16V

PN

Q205BC858ALT1

3

1

2

PC101ASFH817A

21

CN2014324-11S

123456789

1011

ZD201MMSZ6V8T1

Q202

MJD200DPAK

D221

MMSD4148

D210

MBRF20L80CTG

to220

12

3

+

C232470u 16V

PN

R241

2K2

R2082K2

R232 6K19

R215220

+C21747u 25V

R23710K

+C220

470u 16V

PN

R207 4R7

R2111K

D219

MMSD4148

D208MMSD4148

D217

MMSD4148

C20010n 500V

C21068p

R2498K2

D201

1N4937do41d

R25133K 2W

R206

470k

R2101K

Q203STP5NK70ZFP

C211

1n

+C222

470u 16V

PN

R213

470

R2221K

C213

330p

Q204BC808-25LT1

3

1

2

+C208

470u 16V

PN

C230

470nF

IC201

TL431BCLPRA

32

1

C214

100nR216220

R25233K 2W

R2332K49

R2271K

R2364K7

R217 27

VS2

VS1CS

CS

PFC_OUT

PFC-OK

VCC4

V1

Regulation

V2

VS2

Regulation

VS2

VS1

VS1

VS1

VS2

V2

Regulation

V1VS-Stby

VCC3

2_5VREF

46” LCD TV QR Flyback Waveforms• QR mode with valley lock-out

– With valley lock-out for low P– With lower frequency by P Max

• Top Trace– Vin = 400 Vdc Pout = 34 W– 1.75 A at 42.7 kHz – V max = 572 V

• Bottom Trace– Vin = 400 Vdc Pout = 70 W– 2.62 A at 39 kHz– V max = 618 V

Valley lock-out is a Key improvement of QR mode

ECO Standby SMPS Solution (1)

•Dedicated 5W ECO Power Standby SMPS

– Pin < 90 mW for Pout = 40 mW @ 230 Vac

– Integrated High Voltage switcher NCP1053A (400 mA / 40 kHz Max)

• Hysteretic mode improves

• Low frequency mode allows DCM

• Limited current reduces possible noise issues

Hysteretic, Low Freq & DCM for ECO Standby SMPS

ECO Standby SMPS Solution (2)

•Standby relay– Disconnect all “parasitic” standby load (~100-150

mW @ 230 Vac)

– Directly controlled by TV µP

•Optional ECO “ON / OFF switch”– Low cost 2A / 10V non-isolated switch

– OFF mode: Pin < 20 mW by no load @ 230 Vac

ECO switch provides “ON/OFF” without Mains switch

20

30

40

50

60

70

80

0.03 0.04 0.05 0.10 0.25 0.50 1.00 1.50 2.00 4.00 5.00

Output Power (W)

Effic

ienc

y (%

)

Efficiency / 230V

Efficiency / 120V

ECO Standby SMPS efficiency

OFF mode / no load: Pin < 20 mW @ 230 Vac (15 @ 120 Vac) Standby / 40 mW Out: Pin < 90 mW @ 230 Vac (86 @ 120 Vac)

ECO Standby SMPS Waveforms• Drain Voltage and Current of

NCP1053A Switcher– 200 V/div & 200 mA/div

• For 5 V & 1 A = 5 W Output

• Left: Hysteretic Burst mode– (100 µs/div)

• Right: Detailed cycle – (4 µs/div)

• Top Trace: 90 Vac

• Middle Trace: 230 Vac

• Bottom Trace: 264 Vac

ECO Standby SMPS Schematic

VS-Stby

VCC2

VCC1

PC100A

C10710nF

SFH817A

21

R103 8.2K

R1101K

R1011K

Q103

BC848ALT1

CN1014324-05S

12345

Q100BC858ALT1

3

1

2

R120 0

Q101 BC808-25LT13

12

R10410K

+C104

10u 25 V

R11922K

J100INSTALL

12

D100

MBR360

NCP1053P44GIC100

VCC1 GND 8

Control in2

Power Drain 5NC4

GND3

GND 7

R118470

IC101TLV431ASN1

32

1

R115 1K

R1142K2

D104

MMSD4148

1.25VREF

R116 1K

R113 4K7

PC001BSFH817A

43

R100100K 1/4W

D102

BAV21

ZD101 MMSZ5V1T1

R11110K

D108 MMSD4148

CN1004324-02S

12

D105

MMSD4148

R10910K

C100220p 400V

L100

10uH1 2

R10230K

R1174.7K

R1074.7K

PC100B

SFH817A

43

D110 MMSD4148

ZD102 MMSZ15T1

D106MMSD4148

R10510K

T100750871014

7

83

14

5 6

9

R106470

+ C102

470µ 16V

PN

R1121K

R1084.7K

+ C10347µ 25V

PN

+C10547u 25 V

D101 1N4937

D103MMSD4148

D109 MMSD4148

PC200A

SFH817A

21

C106 100 n

PC200B

SFH817A

43

D107

MMSD4148Q102

BC848ALT1

C10110p 1KV

STANDBY

VS-Stby

POWER_OK

RELAY1

VS-Stby

V1

RELAY2

VCC3VCC4

Standby_supply

STANDBY

VS1

Regulation

VS-Stby

VS2

ON-OFF Switch "Optional"

POWER_OK

Standby power and signalTo Signal processing board

HV Barrier

46” Flat TV PSU - Backlight Interface

• Interconnection on Power to any Backlight solutions

– 400 Vdc / 200 W– PFC OK – 5 V and 12 V– Power Good

•Separated & Dedicated Backlight solutions– High Voltage LIPS for CCFL / EEFL– High DC Output Voltage HB LLC for LED Driver– Classical 24 Vdc HB LLC– PDP dedicated Power converter

46”LIPS Inverter• Higher power LCD-TVs

– With extension to 40/42” or 52”/55” for both CCFL or EEFL– Follow on of 32” LIPS Reference Design– Full Bridge fixed frequency ZVS with possible synchronization– High efficiency, low EMI and sinusoidal lamp current

• Dedicated LIPS module– To be interconnected with 46” Power Ref Design Step 1 < 13 mm– Microsemi Backlight controller LX6503

• ON Semiconductor IC’s– 2 High Side Drivers NCP5111– 1 single signal driver transformer

• Low profile design– < 13 mm on top of PCB

Power (PFC + Flyback + Standby SMPS)

LIPS - High Voltage Back-light Inverter

CrM Interleaved PFC

NCP1631400 Vdc

OFF in Stand-by

Full Bridge Inverter

2 x High Side Driver NCP5111

OFF in Stand-by

QR FlybackSMPS

NCP1379OFF in Stand-by

Mains Input90-264 Vac

12 Vdc 5 Vdc

St-by / ONBias

LCD TV Signal

processing and

Audio amplifiers

Back-light Controller

LX6503

CCFL

Current sensing

I Lamp regulation OCP, OVP

PWM 2

PWM 1

13 Vdc Audio

Current balancing

Board

Stand by SMPSNCP1053A

5 Vdc-Stand-by

Open lamps protection

Relay

Power Good

ON/OFF, Dimming,Synchro

ON/OFF

46” LIPS Inverter Block Diagram

46” LED Backlight Power • Higher power LCD-TVs

– With extension to 40/42” or 52”/55”– HB LLC dedicated to Backlight power– High DC output voltage to power directly LED drivers

• Separate / Dedicated LED Power module– To be connected with 46” Power Ref Design step 2 < 8 mm

• ON Semiconductor IC’s– New NCP1397– New – New LED driver controller CAT4206

• Low profile design– < 8 mm on top of PCB (< 12.5 mm total)

Multiple LED Linear Drivers with CAT4026

• Up to 6 channels with linear bipolar transistors Linear: • “Vf monitoring and supply modulation & control”

Dedicated SMPS to support output voltage modulation

46” Linear Edge LED Driver TV Block Diagram

DedicatedSMPS forBacklight

with Modulated

output voltage

46” Linear LED Driver Backlight Solution

Ultra SLIM design < 8 mm / 12.5 mm total

• Special technologies • PCB size: 250 mm x 165 mm

HB LLC for Ultra Slim SMPS

• Limited number of components

• Zero Voltage Switching (ZVS)

• Zero Current Switching (ZCS)

• Higher power density

High efficiency and EMI friendly for low profile SMPS

Resonant Inductance Location?

Benefits:• flexibility• EMI• use resonant coil for OCP

Drawbacks:• cooling• insulation

External resonant coil is better for ultra slim design

External inductance Internal leakage inductance

Benefits:• insulation • cooling • One component

Drawbacks:• flexibility• EMI + stray flux• window utilization

Secondary Rectification

Benefits:• voltage drop• Single diodes

Drawbacks:• secondary winding• matching • window utilization• Higher voltage rectifiers

Bridge rectifier is better for HV output applications

Push-pull configuration Bridge rectifier

Benefits:• one winding • Lower voltage diodes• Matching

Drawbacks:• Higher losses

NCP1397 - LLC Stage Controller

NCP1397 is cost effective and highly safe solution

Features:- operation from 50 kHz up to 500 kHz- 600 V driver- Startup sequence via an externally adjustable soft-start- Brown-out protection combined with latch input- Disable input for ON/OFF control (skip mode)

Benefits for backlight application:• No driver transformer• Simple skip mode • Simple OCP

New OCP Implementation

Res. Coil aux. winding provides accurate and fast OCP

• Adjustable delayed fault • Short circuit protection with frequency shift • New Double phase current information from auxiliary

winding of resonance coil

Output Voltage Modulation

CAT4026 sinkscurrent from FBdivider to increaseoutput voltage

• Linear LED Drivers impact– Dedicated SMPS to support output voltage

modulation – Does not allow to get added auxiliary voltages for

Audio & Signal processing

Single Output Voltage modulated for Linear Driver

HB LLC Schematic for Linear LED Driver

• Strong load variation (0 to 100%) on HB LLC with 100 Hz dimming

• Traces:– Top: Output current from 0 to 1

A (0.5 A/div)– Middle: Primary current 2 A/div– Bottom: Output voltage ripple

2 V/div (120 Vdc)

• Top picture: 50% dimming– HB LLC works in Burst– Up to 3 Vpeak ripple on Vout

• Bottom picture: 5% dimming– HB LLC works in Burst– < 0.5 Vpeak ripple on Vout

HB LLC Waveforms

Edge-LIT LED Backlighting Trends

• ‘LED Light bars’ vary in configuration– Single LED Strings of High Power (~ 200 V+ , 100 mA+)– Multiple LED Strings (up to 4) of Lower Power (~ 100 V+ ,

50 mA+)

LED Driver solutions must handle from 4 to 16 channels

Existing Large Panel Backlight Solution

Advantage: Independent Channel Efficiency and LED-Fault handlingLoosely regulated input supply

Drawback: Cost and Complexity

Loosely ~100V

For each LED channels!

Existing LED Driver Backlight Solution

• Large-size panel power Module used for 6 Channel Edge-LIT LED TV• Each channel has a Dedicated Driver IC + inductive DC/DC boost + switch

6 Ch = 6 x ( DC-DC Boost + additional switch )

6 Ch = 6 x Driver IC

Multi-channel “Linear” Edge-Lit Solution

• Cost effective solution to address a wide number of channels

• VF Monitoring to dynamically adjusts Anode voltage

• Efficiency target range >90%, 94% typ. (varies with LED mismatch)

• Thermal dissipation addressed by external Power BJT’s

• Address various LED string faults

“Linear LED Driver”: A cost effective solution for multiple channels

Multi-channel “Linear” Edge-Lit Solution• 6 channel configuration shown

Fault diagnosticsExternal power devices (low θJA)

LED Cathode regulation ~3 VLED-Anode : dynamic adjustment

LED Cathode OVP

Multi-channel “Linear” Edge Driver Schematic

DPAK or TO220FP Power stage

Current sense

OVP UVP

Connection to the 6 Edge LED segments

Optimized Dynamic LED-Anode ControlTYPICAL EFFICIENCY

80%

85%

90%

95%

100%

0% 5% 10% 15% 20%LED STRING MISMATCH [Pk-Pk]

EFFI

CIEN

CY

200V100V

'LINEAR' POWER DISSIPATION

0

5

10

15

20

0% 5% 10% 15% 20%LED STRING MISMATCH [Pk-Pk]

DIS

SP

ATIO

N [W

ATT

S]

6ch: 200V, 100mA (120W)12ch: 100V, 50mA (60W)

V modulation & control to limit overall Power dissipation

• Efficiency depends on LED string matching • 200V LED strings (with 10% mismatch) delivers ~ 94% efficiency • Thermal power dissipation levels : ~ 5 to 10 watt range

LED Channel Current MatchingVARIATION vs BASE CURRENT

-0.6%

-0.4%

-0.2%

0.0%

0.2%

0.4%

0.6%

0 2 4 6BJT BASE CURRENT [mA]

VA

RIA

TIO

N %

VARIATION vs LED CATHODE

-0.6%

-0.4%

-0.2%

0.0%

0.2%

0.4%

0.6%

3 6 9 12 15 18 21 24 27 30CATHODE VOLTAGE [V]

VAR

IATI

ON

% .

CHANNEL MATCHING %

-1.0%

-0.5%

0.0%

0.5%

1.0%

Ch1 Ch2 Ch3 Ch4 Ch5 Ch5

CHANNEL

MA

TCH

ING

%

• Initial channel matching tolerance ~ ± 0.5%• Variation with BJT Base current : < 0.25%• Variation with Cathode to 30V : < 0.15%• Overall Channel matching less than ± 2%

Very good current matching < +-2%

Optimized Wide PWM Dimming Range

• No concept limitation for very short “ON”time

• CAT4026 Linear Driver is optimized for PWM dimming

• Strong power variation managed directly by SMPS

BRIGHTNESS vs PWM DUTY

0%

1%

10%

100%

0% 1% 10% 100%PWM DUTY CYCLE

CU

RR

ENT

% [

FSB]

Down < 1% for 400Hz PWM dimming

Edge LED Linear Backlighting Summary

• Provides reduced total solution cost

• VF monitoring minimizes & optimizes power dissipation

• Minimizes EMI

• Offers competitive Channel to Channel LED matching

• Offers competitive wide range PWM dimming with good linearity

• Supports Fault diagnostics against Open-LED and Short-LED modes

The Linear is a easy to design and cost effective solution

Conclusion• Complete roadmap of LCD TV solutions

– 32” LIPS• A cost optimized solution for CCFL from 26” up to 42”

– 46” Power• Power for any type of Backlight from 40” up to 55”< 13 or 8

mm– 46” LIPS

• < 13 mm with separate LIPS– 46” Edge LED

• SLIM < 8 mm with separate LED Drivers with very efficient Linear Edge LED driver solution

• Approach– Synergy by re-use solutions, speeding up the design process

For More Information

• View the extensive portfolio of power management products from ON Semiconductor at www.onsemi.com

• View reference designs, design notes, and other material supporting the design of highly efficient power supplies at www.onsemi.com/powersupplies