howled tvs work
TRANSCRIPT
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AC-DC LCD TV Power Architecture
andLED Backlight
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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
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LCD-TV Shipments by Size
Source: Displaysearch 2Q 09
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Power Reduction Trend
• Regulatory reduce powerconsumption in active andstandby mode
• New technologies focusedon improving efficiency
Source: Sharp
• Proposed ENERGYSTAR TV regulations(V4.0) will lower average power targets
Power consumption reduction ~ - 50% over 2 years
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Proposed ENERGY STAR rev4.0 Standards
Target Effective Date: May 2010
Very few LCD-TV pass
proposed new standard,
most are Samsung LED
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LCD-TV LED Backlighting
LED TVs is forecast to grow to 20-32% (~64 M#) by 2012
Source: DisplaySearch July 2009
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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% ?
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Power Architectures Remain Varied
PFCCRM
Interleave FCCrM
CCM
70 - 400+ W
Signal Power Flyback
Resonant HB
30 – 80 W
Backlight Power
Flyback / Resonant HB24V / 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
ECO Standby< 5 W
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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
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32” HV-LIPS LCD TV Block Diagram
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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 mm
All-in-one board with current balancer
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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 profi le design – 1st phase: < 13 mm
– 2nd phase: < 8 mm
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46” LCD TV Power Block Diagram
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46” LCD TV Power Solution Unit (PSU)
Low Profile design < 13 mm / 17.5 mm total
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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
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PFC Summary
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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
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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
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46” LCD TV Flyback Schematic
2_5VREF
D207
MBRF20L80CTGto220
1 2
3
Flyback power to
Signal processing
and Audio board
R228 1K
Backlight
controller
supply to
Backlight
board
D215
MMSD4148
R23810K
R203 33k
R2210.47R 2W CN403
Gnd_Lug
1
+
C206
470u 16V
P
N
D216
MMSD4148
PC101B
SFH817A
4
3
CN2024324-03S
123
R2121K
L201 10uH1 2
+
C219
470u 16V
P
N R2192K2
+
C216
10u 50V
+
C209470u 16V
P
N
L202 10uH1 2
R209 100
R231 16K2
+
C207
470u 16V
P
N
*
*
*
*
*
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
CT 8
FB2
DRV 5
GND4
CS3
BO 7
R255
10M 2W
R2422K2
D205
BAV21
C225
Y 1nF
+
C205
470u 16V
P
N
D211MMSD4148
R22047k
R214
10k
R205
1K
ZD200
MMSZ15T1
+
C221
470u 16V
P
N
Q201BC858ALT1
3
1
2
D209
MMSD4148R218
3K3
Q207BC858ALT1
3
1
2
+
C224470u 16V
P
N
Q205BC858ALT1
3
1
2
PC101A
SFH817A
2
1
CN2014324-11S
123456789
1011
ZD201MMSZ6V8T1
Q202
MJD200DPAK
D221
MMSD4148
D210
MBRF20L80CTG
to220
12
3
+
C232470u 16V
P
N
R241
2K2
R208
2K2
R232 6K19
R215220
+C21747u 25V
R23710K
+
C220
470u 16V
P
N
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
P
N
R213
470
R2221K
C213
330p
Q204BC808-25LT1
3
1
2
+
C208
470u 16V
P
N
C230
470nF
IC201
TL431BCLPRA
3
2
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
V1
VS-Stby
VCC3
2_5VREF
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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
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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
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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
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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)
E f f i c i e n c 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)
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ECO Standby SMPS Waveforms
• Drain Voltage and Current ofNCP1053A 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
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ECO Standby SMPS Schematic
VS-Stby
VCC2
VCC1
PC100A
C10710nF
SFH817A
2
1
R103 8.2K
R1101K
R101
1K
Q103
BC848ALT1
CN1014324-05S
12345
Q100
BC858ALT1 3
1
2
R120 0
Q101 BC808-25LT13
1
2R10410K
+
C104
10u 25 V
R11922K
J100
INSTALL 1
2
D100
MBR360
NCP1053P44GIC100
VCC1 GND 8
Control in2
Power Drain 5
NC4
GND3
GND 7
R118470
IC101TLV431ASN1
3
2
1
R115 1K
R1142K2
D104
MMSD4148
1.25VREF
R116 1K
R113 4K7
PC001B
SFH817A
4
3
R100100K 1/4W
D102
BAV21
ZD101 MMSZ5V1T1
R11110K
D108 MMSD4148
CN1004324-02S
12
D105
MMSD4148
R10910K
C100220p 400V
L100
10uH1 2
R102
30K
R1174.7K
R1074.7K
PC100B
SFH817A
4
3
D110 MMSD4148
ZD102 MMSZ15T1
D106
MMSD4148
R10510K
T100750871014
7
83
14
5 6
9
R106470
+ C102
470µ 16V
P
N
R1121K
R1084.7K
+ C10347µ 25V
P
N
+
C105
47u 25 V
D101 1N4937
D103MMSD4148
D109 MMSD4148
PC200A
SFH817A
2
1
C106 100 n
PC200B
SFH817A
4
3
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 signal
To Signal processing board
HV Barrier
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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
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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 control ler LX6503
• ON Semiconductor IC’s – 2 High Side Drivers NCP5111
– 1 single signal driver transformer
• Low profile design – < 13 mm on top of PCB
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Power (PFC + Flyback + Standby SMPS)
LIPS - High Voltage Back-light Inverter
CrM Interleaved
PFC
NCP1631
400 VdcOFF in Stand-by
Full Bridge Inverter
2 x High Side Driver
NCP5111
OFF in Stand-by
QR FlybackSMPS
NCP1379
OFF in Stand-by
Mains Input
90-264 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 SMPS
NCP1053A5 Vdc-
Stand-by
Open lamps
protection
Relay
Power Good
ON/OFF, Dimming,Synchro
ON/OFF
46” LIPS Inverter Block Diagram
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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)
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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
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46” Linear Edge LED Driver TV Block Diagram
Dedicated
SMPS for
Backlight
with
Modulated
output vol tage
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46” Linear LED Driver Backlight Solution
Ultra SLIM design < 8 mm / 12.5 mm total
• Special technologies
• PCB size: 250 mm x 165 mm
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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
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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
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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
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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
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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 auxiliarywinding of resonance coil
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Output Voltage Modulation
CAT4026 sinks
current from FB
divider 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
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HB LLC Schematic for Linear LED Driver
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• 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 ripple2 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
Ed LIT LED B kli hti T d
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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
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E i i LED D i B kli h S l i
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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
M lti h l “ Li ” Ed Lit S l ti
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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
M lti h l “ Li ” Ed Lit S l ti
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Multi-channel “ Linear” Edge-Lit Solution
• 6 channel configuration shown
Fault diagnosticsExternal powerdevices (low JA)
LED Cathode regulation ~3 VLED-Anode : dynamic adjustment
LED Cathode OVP
Multi channel “ Linear” Edge Driver Schematic
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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 Control
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Optimized Dynamic LED-Anode Control
TYPICAL EFFICIENCY
80%
85%
90%
95%
100%
0% 5% 10% 15% 20%
LED STRING MISMATCH [Pk-Pk]
E F F I C I E N C Y
200V
100V
'LINEAR' POWER DISSIPATION
0
5
10
15
20
0% 5% 10% 15% 20%
LED STRING MISMATCH [Pk-Pk]
D I S S P A T I O
N [ W A T T 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 Matching
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LED Channel Current MatchingVARIATION vs BASE CURRENT
-0.6%
-0.4%
-0.2%
0.0%
0.2%
0.4%
0.6%
0 2 4 6
BJT BASE CURRENT [mA]
V A
R I A T I O 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 30
CATHODE VOLTAGE [V]
V A R I A T I O N %
.
CHANNEL MATCHING %
-1.0%
-0.5%
0.0%
0.5%
1.0%
Ch1 Ch2 Ch3 Ch4 Ch5 Ch5
CHANNEL
M A T C
H I N G %
• Init ial 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%
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Edge LED Linear Backlighting Summary
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Edge LED Linear Backlighting Summary
• Provides reduced total solution cost
• VF monitoring minimizes & optimizes power dissipation
• Minimizes EMI
• Offers competit ive 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
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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
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