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TPS2553: FAULT not asserted for current limit

Shareef Jalloq7
Prodigy 80 points
Part Number: TPS2553

Hi,

I'm testing the TPS2553 in our application and we have set the current limit threshold for 1.5A.  I can hook up a constant current load and increase this past the threshold.  The TPS2553 seems to detect the current limit correctly and limits the output but does NOT assert the FAULT# output.

I thought the datasheet describes this behaviour so what could be wrong?  I previously raised an issue regarding the failure of the device to assert FAULT for its advertised reverse voltage protection feature.  Is this another example of something that doesn't work on this part?

Shareef.

  • 0
    TI__Expert 8980 points
    Hi, Shareef,

    Vin ripple might be the reason. I guess TPS2553 Vin supply of your application is a DC-DC converter, right? If yes, can you take below action:
    1. Monitor Vin ripple, and check how worse the ripple is.
    2. Use DC power supply to supply Vin for TPS2553, and check if fault will asset at current limit condition.

    Regards,
    Bob
  • 0 in reply to Bob Ma
    Prodigy 80 points
    Hi Bob,

    thanks for that, however, I found my issue. It was user error in testing. It seems that our software stack changed between the two products that I was testing and the latest model disables and re-enables the USB switch when it faults. I was looking for FAULT# being asserted and missed that it was toggling at a high frequency.

    Cheers.
  • 0 in reply to Shareef Jalloq7
    TI__Expert 8980 points
    Hi, Shareef,

    Good to know it. Feel free to reach out if any question.

    Regards,
    Bob