ViewSonic VX712

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ViewSonic Corporation
Confidential - Do Not Copy VX712
4.3 PWPC BOARD BLOCK FUNCTION DESCRIPTION
PWPC board combines to adapter and inverter, Adapter which commonly consists of
bridge rectifier and filter, start circuit, PWM control circuit, protection circuits and convert to
12V, 5V DC voltage by input 90V-240V AC voltage that provide power supply for each
chips in the main board and inverter. Inverter is DC TO AC circuit. It changes the 12v DC
of power supply to about 600-800v AC that drives the backlight. It mostly consists of
starting circuit, PWM controller, DC changing circuit, LC surging circuit, output circuit and
protection circuit etc.
AC input
EMI filter
Bridge
Rectifier
and Filter
Start Circuit
R903, R904,R905
PWM
Control IC
Over
Voltage
Protect
Rectifier
CMOS
ON/OFF
Control
PWM
Control IC
Feedback
Circuit
OSC and
Output
Circuit
DC Convert
Circuit
MOSFET
Q203
Over
Voltage
CN902
Transformer
Lamp
5V
12V
ON/OFF
DIM