Dc/Dc Converters; Led Drivers; C-Balancing Concept For Led Driving - Philips 32PFL8605H/12 Service Manual

T co n 2 0 0 H z
S h a rp
A S IC A S IC
P N X P N X
5120 5120
LVD S splitter
1G5 1
1G5 0 1G5 1
B ac k lightB oos t
P N X
85500
Lam p
S S B T V 5 5 0
Figure 7-15 Backlight application (xxPFL9xxx sets 40" & 46"
200 Hz "2D" scanning)
T co n 2 0 0 H z 3D
S h a rp
A S IC A S IC
F P G A
P N X P N X
5120 5120
LVD S splitter
1G5 1
1G5 0 1G5 1
B ac k lightB oos t
P N X
85500
Lam p
S S B T V 5 5 0
Figure 7-16 Backlight application (xxPFL9xxx sets 58" 21:9 (3-d)
200 Hz "2D" scanning)
7.3.1

LED Drivers

The traditional concept for the LED drivers uses
• Linear drivers, or
• DC/DC drivers.
This concept has been explained in previous Service Manuals.
B a ckL ig h t
D ire ctL E D
B L-I2S
sca n n in g
PWM
2D-D I M
-
O N
P S D L
18750_205_100415.eps
100423
B a ckL ig h t
D ire ctL E D
B L-I2S
sca n n in g
PWM
2D-D I M
-
O N
P S D L
18750_206_100415.eps
100423
Circuit Descriptions
Some sets use an alternative "balancing" concept
with the use of
• C-balance drivers, or
• L-balance drivers (currently not implemented).
This introduces the "C-balancer board" for some of the
xxPFL9xxx sets.

C-balancing Concept for LED driving

The advantages of the C-balancing concept are:
• Cost reduction
• Higher efficiency
• Higher reliability, because of less components used.
The C-balance drivers and -components are mounted on a
separate C-balancer board. This PWB is mounted on the LCD
panel by the LCD manufacturer, though developed by Philips.
There are two possible configurations:
• For edge-lit displays & direct-lit displays + "0D" dimming
• For direct-lit displays + "2D" dimming.
Refer to Figure 7-17
Power
Conversion 1
AC
in
Part of Power Supply
Figure 7-17 Balancing LED-drivers application for edge-lit
displays & direct-lit displays in combination with "0D" dimming
Power
Conversion 1
AC
in
Part of Power Supply
Figure 7-18 Balancing LED-drivers application for direct-lit
displays in combination with "2D" dimming
7.4

DC/DC Converters

The on-board DC/DC converters deliver the following voltages
(depending on set execution):
• +3V3-STANDBY, permanent voltage for the Stand-by
controller, LED/IR receiver and controls; connector 1M95
pin 1
• +12V, input from the power supply for TV550 common
(active mode); connector 1M95 pins 6, 7 and 8
• +24V, input from the power supply for DVB-S2 (in active
mode); connector 1M09 pins 1 and 2
• +1V1, core voltage supply for PNX85500; has to be started
up first and switched "off" last (diagram B03B)
• +1V2, supply voltage for analogue blocks inside
PNX85500
• +1V8, supply voltage for DDR2 (diagram B03B)
• +2V5, supply voltage for analogue blocks inside
PNX85500 (see diagram B03E)
• +3V3, general supply voltage (diagram B03E)
• +5V, supply voltage for USB and CAM (diagram B03E)
• +5V-TUN, supply voltage for tuner (diagram B03E)
back to
div. table
Q551.1E LA 7.
and Figure 7-18 for the application.
Power
Conversion 2
DC to LED-drivers)
Rectifier
R e s o n ant
380 to to p o lo g y
Balan cin g 1
4 0 0 V
DC
D rive r-part Balan cin g 2
Balan cin g 3
Balan cin g n
18750_209_100415.eps
Power Power
Conversion 2a Conversion 2b
DC to LED-drivers) DC to LED-drivers)
Rectifier
R e s o n ant
380 to to p o lo g y
Balan cin g 1
4 0 0 V
DC
D rive r-part Balan cin g 2
Balan cin g 3
Balan cin g n
18750_210_100415.eps
EN 61
Backlight-unit
(LED-strings)
Part of Display
100416
Backlight-unit
(LED-strings)
Part of Display
100416
2010-Oct-01