ViewSonic VSXXXXX service manual Block Diagram Pin, Comp GND OUT VCC

Block Diagram

Pin Name

1CT

2COMP

3CS

4GND

5OUT

6VCC

7NC

8HV

Function

This pin is to program the frequency of the low frequency timer. By connecting a capacitor to ground to set the OLP delay time. And this pin can be used for latch mode protection. By pulling this pin lower than 0.8 V, the controller will be entered latch mode until the AC power-on recycling.

Voltage feedback pin (same as the COMP pin in UC384X), By connecting a photo-coupler to close the control loop and achieve the regulation. A high quality ceramic capacitor (X7R) is required for general applications (102pF at least).

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 terminal 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.

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