ViewSonic VA703b Service Manual page 20

LD7575 PS (IC901): The LD7575 is a current-mode PWM controller with excellent
power-saving operation. The embedded over voltage protection, over load
protection and the special green-mode control provide the solution for users to
design a high performance power circuit easily and etc. The function of each pin
and the inside circuit diagram are as follows:
PIN Descriptions:
Pin Name
1 RT
2 COMP
3 CS
4 GND
5 OUT
6 VCC
7 NC
8 HV
Block Diagram
ViewSonic Corporation
This pin is to program the switching frequency. By connection a
resistor to ground to set the switching frequency.
Voltage feedback pin(same as the COMP pin in UC384X), By
connecting a photo-coupler to close the control loop and achieve the
regulation.
Current sense pin, connect to sense the MOSFET current
Ground
Gate drive output to drive the external MOSFET
Supply voltage pin
Unconnected Pin
Connect this pin to positive of bulk capacitor to provide the startup
current for the controller, when Vcc voltage trips the UVLO(on), this
HV loop will be off to save the power loss on the startup circuit.
Confidential - Do Not Cop
Function
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VA703b/VA703m