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UCC28180: question about VSENSE < VCC pin

Masazumi Ishii
Genius 3945 points
Part Number: UCC28180

Hello

I have a question about UCC28180.

Question 1
The PFC (UCC 28180) was turned off from the on state using the measurement power supply. At this time, the potential of the following terminals of UCC28180 is temporarily reversed.
Do you need any measures in this situation?
Also, if it is necessary to take measures, is it better to connect a diode from VSENSEpin to VCCpin?

<On the potential>
・ Measurement power ON state: VCC> V SENSE
? When switching the measurement power supply from ON to OFF: VCC <VSENSE

Thank you.

  • 0
    TI__Mastermind 34465 points

    Hi ,

    This is a normal operating condition for the UCC28180 during power up and power down.

    There is no requirement to add a diode from VSENSE to VCC.

    When the pfc first turns on there is a voltage on the pfc output and on VSENSE.
    The pfc output then generate the VCC bias voltage from a small flyback power supply.
    Also you can turn off the pfc controller by removing the VCC voltage and still having a voltage on VSENSE.

    Regards

    John