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UCC28220: Soft Start

Kevin Xiong
Expert 2340 points
Part Number: UCC28220
Other Parts Discussed in Thread: UCC28221

Hi,

Our customer is using UCC28220. He finds that there is no Soft-Start function. He applies the power on VDD first and then increasing VIN voltage to 240V. Could you please tell us how to get the Soft-Start function? And the normal power up sequence?

Thanks.

Kevin Xiong

  • 0
    TI__Intellectual 2640 points

    Hi Kevin! 

    Thanks for reaching out and for your interest in the UCC28220. Do you have a capacitor connected to the SS pin? The sizing of this capacitor (as well as the sizing of the CHG resistor) determines the soft start speed. 

    The VIN pin is a NC pin on the UCC28220, is your customer maybe using the UCC28221? 

    Thanks again for getting in touch, I look forward to talking more soon!  

    Aidan Davidson