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TPS25981: TPS259814L failing S/C

Andrew Pettifer
Prodigy 70 points
Part Number: TPS25981

Tool/software:

Hi 

I am investing an issue on our prototype board where the eFuse is failing sometimes short circuit (well measuring 7ohms on DVM in both directions)  the UVLO is not operating and the device just passed input to output.  We are not sure what is causing the device to blow in this way and are concerned it is able to blow in this way as it is a protection device so one would assume short not fail s/c?

This is our schematic the downstream load is a 3v3 SM regulator supplying an un programmed arm processor taking about 60mA so very lightly loaded.  We have 10uF cap on the input to the upstream SM PSU circuit.

  

Any help much appreciated 

  • 0
    TI__Mastermind 39045 points

    Hi Andrew,

    Did reverse current flow through the device? If yes, then it is possible that body diode of main FET got damaged while making short between the IN and OUT. The body diode do not support continuous high current flow. 

    As such, I don't see any issue in schematic which will immediately cause this issue. (decoupling caps are missing but that should cause this)

    Can you tell me more about the test you did. Is it output short circuit when device is in normal operation. By any chance do you have waveforms with current, Vout, Vin probed. Is there any Vin or Vout abs max violation.

    Best Regards,
    Arush