LG 42LV5500 Training Presentation page 41

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
primary section (Power Factor Controller circuit) increases its current supplying ability. i ti (P
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 3.5V_ST (3.55V) output P201 pins 9 12
12V (12V) output P201 pins 17, 19 and 21
24V (24V) output P201 pins 2, 3 and 4.
P202 Connector: (To Panel LEDs)
45V output P202 pins 1 and 12. 45V t t P202 i
F t C t ll i
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1 d 12
it) i it
P203 Connector: (To Panel LEDs)
45V output P203 pins 1 and 13. 45V output P203 pins 1 and 13
P832 Connector: (To the Main Board)
This connector receives the Local Dimming signals.
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t l i bilit
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May 201 1 LCD TV 42LV5500
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