ViewSonic VP950B - Page 21

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ViewSonic Corporation
Confidential - Do Not Cop VP950b
Circuit Diagram
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 Function
1 RT
This pin is to program the switching frequency. By connection a
resistor to ground to set the switching frequency.
2 COMP
Voltage feedback pin(same as the COMP pin in UC384X), By
connecting a photo-coupler to close the control loop and achieve the
regulation.
3 CS Current sense pin, connect to sense the MOSFET current
4 GND Ground
5 OUT Gate drive output to drive the external MOSFET
6 VCC Supply voltage pin