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TPS22917: Inrush

Allan Fan
Expert 7080 points
Part Number: TPS22917

Tool/software:

Hi expert,

Customer tried TPS22917EVM on their pcb input path. Here is the test condition:

1. the total output capacitor from TPS22917 point of view is about 4xuF.

2. CT = 1000pF. 

3. Vin = 5V

Would you please advise how to set the CT to make inrush current below 500mA and what might be possible reasons we still see a high inrush current 1.68A with this configuration?

Regards,

Allan

  • 0
    TI__Intellectual 2470 points

    Hi Allan,

    A CT of 1000pf should be plenty to prevent of 500mA inrush current in normal conditions if the Cl is 40uF.

    Looking at your waveform I see a lot of ringing from VIN which may be causing this problem. If you place a capacitor on VIN it may help solve this problem. In addition letting Vin settle to a stable condition before turning the enable pin on could also help mitigate the problem.

    Best Regards,
    Nicholas