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 Very few LCD-TV pass proposed new standard, most are Samsung LED Target Effective Date: May 2010 LCD-TV LED Backlighting Source: DisplaySearch July 2009 LED TVs is forecast to grow to 20-32% (~64 M#) by 2012 Comparison of LED LCD TV Backlight Options LED driver Merit Concerns Edge-lit LED BLU Direct-type LED BLU High voltage Boost, buck, linear with Vf adjustment Boost or Buck plus Multi-channel linear • High Power Efficiency • Good system reliability independent LEDs performance. • Cost down of system • Slim LCD TV • • • • • • System Noise & EMI • Using lots of external components (Inductor, capacitor, diode) • Thermal limitations • High system cost due to number of LEDs and # of Drivers • Picture artifacts Edge LED > 90% ? Deep blacks, better contrast Local dimming Scanning for higher frame rate Low power consumption Complex signal processing Power Architectures Remain Varied Signal Power Flyback Resonant HB 30 – 80 W PFC CRM Interleave FCCrM CCM 70 - 400+ W ECO Standby <5W Backlight Power Flyback / Resonant HB 24V / 150V+ for LED HV-LIPS for CCFL / EEFL 50 – 300 W Traditional 24 V Backlight and HV-LIPS approach Thin TV design impacts solutions choices as well 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 12 CCFL 175 mm x 330 mm x 25 mm All-in-one board with current balancer Green Point Reference design documentation: http://www.ONSemiconductor.com/pub_link/Collateral/TND3 60-D.PDF 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 CrM PFC – 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 3 BD1 GBU806 Gnd_Lug CN401 D1 1 - + L2 200uH C3 C1 0.47uF 450V C4 Y 1nF 5 6 * nc 9 8 7 11 * 2 50uH 2 L1 1 C2 0.47uF 450V R1 1M Y 1nF R2 1M 3 4 10 9 7 6 * D3 L3Q2 MUR550APF 275V 1 8.7mH Q3 BC808-25LT1 R15 1M CFS28 1 3 R42 1 68u 47 R3 X2 1uF R12 NA 1K O_UVP 275V 0.065 2 W 5% 2 C10 NA R39 1K INSTALL 1 C11 NA R11 J106 MMSD4148 R28 1M 8.7mH C12 Backlight Input Power and Signal R24 1K5 R30 24K D8 3 L5 450V 47 R20 1M 4 CN003 4324-07S 1 2 3 4 5 6 7 8 450V R13 1M 10K R6 2 68u C6 + R7 10K 3 L4 Q4 BC808-25LT1 3 2 3 R10 1M R43 1 R9 1M 4 C7 10nF 500V 1 3 D5 MMSD4148 C8 + D6 MMSD4148 2 Q1 STP9NK50ZFP 2 R8 1M 2 PFC_OUT R5 1M Q2 STP9NK50ZFP CFS28 1 NTC 2R5 PFC_OUT 2 X2 100nF RT1 D2 MUR550APF L2Q1 R4 1M L3 200uH 2 1 * C5 1N5406 4 FB_PFC R16 22K ZCD1_10 R17 150K R18 150K R19 150K IC1 NCP1631 R14 22K R23 150K 4 5 6 RELAY1 BO_PFC RELAY2 7 8 C21 C13 Rt DRV1 OSC GND Vcontrol Vcc Freq-Fall Back BO DRV2 Latch OFF OVP/UVP CS VCC4 PFC-OK 14 R27 47k 13 Q6 12 11 C15 10 100n 1 2 4 3 220n R29 120K C19 C17 1nF C18 220p R31 20K R41 270K O_UVP R33 39K Q5 1 BC856ALT1 POWER_BOOST BC856ALT1 9 680n 220n R25 15K 1 R38 1K C20 SW1 R26 2K2 2 R22 150K 16 15 10n C22 R34 10K NA R37 1K R36 10k + R35 0 C16 RELAY SPST 10u 50V D11 1N4007 2 R21 150K PFC-OK 3 3 ZCD1 FB 1 2 FB_PFC ZCD2 2 1 3 ZCD1_1 PC001A SFH817A F1 FUSE 6A-250V F2 4R7 1W Standby_supply LINE_NEUTRAL RV5 90-264_VAC_INPUT TVR10471KSY L FG CN001 4333-W05ST FG FG N + + C24 3.3 uF 400V C25 3.3 uF 400V 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 T200 750875731 1 PFC_OUT R251 33K 2W C200 10n 500V * D201 1N4937 do41d 11 P 3 P R252 33K 2W + 2 + C207 D207 C208 N 1 N * 470u 16V 470u 16V 3 D205 R203 33k R207 4R7 + C217 47u 25V R213 470u 16V P Q201 BC858ALT1 BO CS VCC Q203 STP5NK70ZFP 6 3 470u 16V 470u 16V V1 + 8 7 CS C225 + 2 Q205 BC858ALT1 Q204 BC808-25LT1 R222 1K Regulation V2 10M 2W 3 R236 4K7 D215 R226 1K D217 1 VS-Stby R227 1K C230 470nF 2 R241 R231 16K2 2K2 1 MMSD4148 VS1 VS2 R238 10K VS2 3 D219 2_5VREF 2 VS1 R233 2K49 D221 P MMSD4148 R232 6K19 + R242 2K2 MMSD4148 N 1 TL431BCLPRA C232 470u 16V VS1 Regulation R228 1K CN202 4324-03S 1 2 3 Backlight controller supply to Backlight board Q207 BC858ALT1 3 2 MMSD4148 R237 10K D216 IC201 VS2 MMSD4148 V1 SFH817A R223 1K 1 R255 R209 100 PC101A D211 MMSD4148 1 VCC4 SFH817A C224 470u 16V Y 1nF 3 4 R219 2K2 MBRF20L80CTG Gnd_Lug CN403 R221 0.47R 2W R220 47k 1 10u 50V 470u 16V 3 3K3 100n C216 470u 16V 1 3 C215 220p C218 100p 1KV 2 1n 2 to220 R218 R249 8K2 VS1 + C220 N DRV C212 10uH 2 + C219 N GND D210 5 MMSD4148 C211 R211 1K L202 1 R217 27 4 Regulation 10 9 * R212 1K P C222 N R215 MJD200 220 DPAK R216 220 100n R210 1K + C221 C214 7 D209 C210 68p P + 8 P 3 CS FB Q202 D208 MMSD4148 1 P CT 470 N ZCD C213 330p 2 PC101B R208 2K2 C209 470u 16V N 470u 16V 5 P 1 VS2 + ZD201 MMSZ6V8T1 IC200 NCP1379 2 C206 2 D206 MMSD4148 C205 N ZD200 MMSZ15T1 R206 MMSD4148 10uH + N R214 10k D203 + BAV21 470k L201 1 N * * P PFC-OK V2 12 6 VCC3 P R205 1K to220 MBRF20L80CTG CN201 4324-11S 11 10 9 8 7 6 5 4 3 2 1 Flyback power to Signal processing and Audio board 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 ECO Standby SMPS efficiency 80 Efficiency (%) 70 60 50 Efficiency / 230V 40 Efficiency / 120V 30 20 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) 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 T100 750871014 3 D101 1N4937 D100 9 8 1 4 L100 1 + MBR360 7 6 2 10uH 5 C102 PC100A 470µ 16V R101 1K 2 C101 10p 1KV R102 30K SFH817A 1 VCC3 2 1 C103 47µ 25V 1 R105 10K IC101 TLV431ASN1 3 R120 0 BAV21 MMSD4148 HV Barrier R114 2K2 VS-Stby 4 PC200B P + D102 VCC1 R113 4K7 100 n 1.25VREF MMSD4148 D105 ON-OFF Switch "Optional" N VCC2 C106 R104 10K 2 VCC4 CN100 4324-02S VS-Stby D104 Q101 BC808-25LT1 3 2 2 1 J100 INSTALL 1 C100 220p 400V P R100 100K 1/4W N Standby_supply D109 MMSD4148 V1 3 SFH817A Regulation D108 MMSD4148 STANDBY RELAY1 D110 MMSD4148 ZD101 MMSZ5V1T1 RELAY2 VS1 R103 8.2K GND PC200A D106 MMSD4148 GND 7 R109 10K R110 1K D107 GND R116 1K R115 1K BC848ALT1 R118 470 R117 4.7K C107 10nF VS-Stby 4 NC Power Drain VS2 Q103 BC848ALT1 5 MMSZ15T1 R112 1K MMSD4148 Q102 4 POWER_OK PC001B SFH817A 3 SFH817A 3 3 ZD102 Q100 BC858ALT1 R111 10K 2 4 Control in R108 4.7K 1 SFH817A 2 PC100B D103 MMSD4148 3 VCC 8 C105 47u 25 V 1 1 R107 4.7K + IC100 NCP1053P44G 2 R106 470 + C104 10u 25 V R119 22K POWER_OK VS-Stby STANDBY CN101 4324-05S 5 4 3 2 1 Standby power and signal To Signal processing board 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 46” LIPS Inverter Block Diagram LIPS - High Voltage Back-light Inverter Full Bridge Inverter 2 x High Side Driver NCP5111 OFF in Stand-by Current balancing Board Current sensing CCFL I Lamp regulation OCP, OVP PWM 1 PWM 2 Open lamps protection Back-light Controller LX6503 ON/OFF, Dimming,Synchro CrM Interleaved PFC NCP1631 400 Vdc OFF in Stand-by QR Flyback SMPS NCP1379 OFF in Stand-by 12 Vdc 5 Vdc 13 Vdc Audio Power Good Relay St-by / ON Bias Mains Input 90-264 Vac Stand by SMPS NCP1053A ON/OFF 5 VdcStand-by Power (PFC + Flyback + Standby SMPS) LCD TV Signal processing and Audio amplifiers 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 Dedicated SMPS for Backlight with Modulated output voltage 46” Linear LED Driver Backlight Solution • • Special technologies PCB size: 250 mm x 165 mm Ultra SLIM design < 8 mm / 12.5 mm total 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? External inductance Benefits: • flexibility • EMI • use resonant coil for OCP Drawbacks: • cooling • insulation Internal leakage inductance Benefits: • insulation • cooling • One component Drawbacks: • flexibility • EMI + stray flux • window utilization External resonant coil is better for ultra slim design Secondary Rectification Push-pull configuration Benefits: • voltage drop • Single diodes Drawbacks: • secondary winding • matching • window utilization • Higher voltage rectifiers Bridge rectifier Benefits: • one winding • Lower voltage diodes • Matching Drawbacks: • Higher losses Bridge rectifier is better for HV output applications NCP1397 - LLC Stage Controller Features: - operation from 50 kHz up to 500 kHz - 600 V driver - Startup sequence via an externally adjustable softstart - 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 NCP1397 is cost effective and highly safe solution New OCP Implementation • Adjustable delayed fault • Short circuit protection with frequency shift • New Double phase current information from auxiliary winding of resonance coil Res. Coil aux. winding provides accurate and fast OCP Output Voltage Modulation CAT4026 sinks current from FB divider to increase output 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 HB LLC Waveforms • 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 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 Loosely ~100V For each LED channels! Advantage: Independent Channel Efficiency and LED-Fault handling Loosely regulated input supply Drawback: Cost and Complexity 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 LED-Anode : dynamic adjustment Fault diagnostics LED Cathode OVP LED Cathode regulation ~3 V External power devices (low θJA) Multi-channel “Linear” Edge Driver Schematic Connection to the 6 Edge LED segments OVP UVP DPAK or TO220FP Power stage Current sense Optimized Dynamic LED-Anode Control 'LINEAR' POWER DISSIPATION TYPICAL EFFICIENCY 100% 20 DISSPATION [WATTS] 200V 100V EFFICIENCY 95% 90% 85% 15 10 5 0 80% 0% 5% 10% 15% 20% LED STRING MISMATCH [Pk-Pk] • • • 6ch: 200V, 100mA (120W) 12ch: 100V, 50mA (60W) 0% 5% 10% 15% 20% LED STRING MISMATCH [Pk-Pk] Efficiency depends on LED string matching 200V LED strings (with 10% mismatch) delivers ~ 94% efficiency Thermal power dissipation levels : ~ 5 to 10 watt range V modulation & control to limit overall Power dissipation LED Channel Current Matching 0.6% VARIATION vs BASE CURRENT CHANNEL MATCHING % 1.0% 0.2% MATCHING % VARIATION % 0.4% 0.0% -0.2% -0.4% -0.6% 0 2 4 6 BJT BASE CURRENT [mA] VARIATION % . 0.4% 0.0% -0.2% -0.4% Ch1 Ch2 Ch3 Ch4 Ch5 Ch5 -0.5% CHANNEL • • • • 0.2% 0.0% -1.0% VARIATION vs LED CATHODE 0.6% 0.5% 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% -0.6% 3 6 9 12 15 18 21 24 27 30 CATHODE VOLTAGE [V] Very good current matching < +-2% Optimized Wide PWM Dimming Range BRIGHTNESS vs PWM DUTY CURRENT % [FSB] 100% • No concept limitation for very short “ON” time • CAT4026 Linear Driver is optimized for PWM dimming • Strong power variation managed directly by SMPS 10% 1% 0% 0% 1% 10% PWM DUTY CYCLE 100% 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