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UCC28950: About UCC28950's Current Limit Current and Hiccup Mode

Paul Lai
Prodigy 30 points
Part Number:

According datasheet's diagram(as below ), we know that when current limit start working, the control IC

will into cycle-by cycle, then it have a small duty and detect CS's voltage during same time, if still over current as  we setting ,

then the ic will turn off all duty during the off time.

My question is, is there have any method if we want to stay cycle by cycle ,dont into the off time? we want duty continue  output when over current , till we  exclude the over current condition, thanks!

 

  • 0
    TI__Mastermind 25570 points

    Hello Paul

    A resistor from VREF to the SS/EN pin will prevent the IDS current from pulling the SS/EN pin below the 3.6V threshold. The resistor value is  R < (VREF - V_pullupthreshold)/IDS  - Probably a value of around 62kOhms would work.

    The idea is that the internal IDS current source cannot discharge the SS/EN capacitor below the 3.6V pull up threshold.

    If you want the controller to shut down in this condition then you will need an external circuit which can pull the SS/EN pin down to GND.

    Regards
    Colin