Feedback Circuit And Photo Coupler; Secondary Rectifier And Filter - BenQ MP611 Product Service Manual

5.8 Feedback circuit and photo coupler

C750
22U
50V
(EL)
105C
The power supply adapt a single feedback circuit of 12V. It used IC750 for voltage
IC652 for primary-secondary isolation. The output voltage will be controlled by IC750 pin 1 (feedback) ,the
duty cycle of MOSFET will be decided to control the output voltage.

5.9 Secondary rectifier and filter

T651
Since the transformer T651 acts as a storing energy inductance , Diode D703 is rectifier and
capacitor C709 is to reduce the output ripple and noise.
R750
1206J
360
IC652
PC123
R706
4 1
1K
0805J
3 2
R751
0805F
K
+
R
IC750
A
TL431
2.5V
D703
+
C709
GND
12V
R753
1.2K
1%
1206F
2.87K 1%
C751
0.1U
50V
0805
R754
10K
1%
0805F
148
2.5V
regulation and