LG 42LV5500 - POWER SUPPLY SECTION

POWER SUPPLY SECTION
This switch mode power supply develops Stand By 3.5V at all times when AC is applied. At
power on, it develops 12V and 24V for the Main board.
It develops
45V
for the LED Backlights
It
develops
45V
for
the
LED
Backlights
.
This power supply draws less than 1 watt during stand by mode. The fuse F101 and F501 reads
approximately 398V (from hot ground) during this time. The transformer T501 delivers an AC signal
which is rectified and filtered by D201, D202, C201 and C202 which develops a Stand-By voltage of
3.55V which is used by the SMPS Controller circuit and is also sent to the Main Board. It is output
3.55V
which
is
used
by
the
SMPS
Controller
circuit
and
is
also
sent
to
the
Main
Board.
It
is
output
P201 pins 9~12 and sent to the P502 on the Main Board.
When the controller chip on the back side of the SMPS receives the PWR-ON command 3.41V via
P201 Pin 1, it turns on the Relay RL101 which supplies AC to the bridge rectifier BD101. The
iti
(P F t C t ll i it) i
it t l i bilit
pr
i
mary sec
ti
on
(P
ower
F
ac
t
or
C
on
t
ro
ll
er c
i
rcu
it)
i
ncreases
it
s curren
t
supp
l
y
i
ng a
bilit
y.
Both Primary fuses F101 and F501 now read a little more than 396V.
D253 receiving switching pulses from L601 develops the 45V for the LED backlights.
When the SMPS receives the DRV
_
ON command from the Main board via P201 Pin 18
(
3.26V
)
it
_()
turns on the on-board Inverter to start driving the LED backlights. The backlight brightness is
controlled by the Main board via PWM Pin 22 and Local Dimming signals via P832.
P201 Connector: (To Main Board)
3 5V ST (3 55V) output P201 pins 9
~
12
P203 Connector: (To Panel LEDs)
45V output P203 pins 1 and 13
3
.
5V
_
ST
(3
.
55V)
output
P201
pins
912
12V (12V) output P201 pins 17, 19 and 21
24V (24V) output P201 pins 2, 3 and 4.
P202 Connector: (To Panel LEDs)
45V t t P202 i 1 d 12
45V
output
P203
pins
1
and
13
.
P832 Connector: (To the Main Board)
This connector receives the Local Dimming signals.
May 2011 LCD TV 42LV5500
41
45V
ou
t
pu
t
P202
p
i
ns
1
an
d
12
.