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UC2845A: UC2845A Question about ON / OFF function by using the COMP terminal.

Part Number: UC2845A

Dear support member

My customer used UC2845A.

I have a question.


(Situation)
My customer thinking the external ON / OFF function by using the COMP terminal.
Specifically, when the input voltage exceeds a certain voltage, the control IC is operated
(Do not start the power supply at low input voltage) specifications.


Connect an NPN transistor (Tr) between COMP and GND,
and when the transistor is OFF Control IC ON.
(The COMP terminal voltage becomes 1.4 V or less at * COMP terminal outflow current 2 mA or more and the control IC OFF)


By using the above function, we are considering a specification that does not operate the control IC at low input voltage.

(Question)
In the normal operation of turning on the control IC, Tr is always in the OFF state.
⇒ When the COMP terminal voltage becomes 1.4 V or less, the control IC turns OFF,
Is Tr is always OFF and there is no problem?

Best regard.
Bob Lee.