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TPS54350: Instability issues

Carlos Silva85
Expert 4915 points
Part Number: TPS54350

My account used TPS54350 as local power supply in many products.

The power supply work OK at room temperature and at very cold temperatures (-25) . But we experience unstable performance at high temperature (+55°C) with a fault rate of approximately 5%. The issue seems to be solved with an increase of the inductor value (10 -> 33uH), but we want to make sure there are no side effects or have the circuit reviewed to potentially determine other causes,

I have some data I could share privately. Any advice welcome.

  • 0
    TI__Mastermind 35165 points

    Hi Carlos,

    I contacted you through e-mail so that you can share the full details with us.

    Best Regards,
    Anthony

  • 0 in reply to Anthony F
    TI__Mastermind 35165 points
    I'm going to mark this resolved for now since we are handling it through e-mail. Alec will update the post once we get to a real resolution through e-mail.
  • 0 in reply to Anthony F
    TI__Prodigy 580 points
    After looking more into this issue, we found that it was related to a few different factors:

    1) The use of the part in non-synchronous mode
    2) The inductor value
    3) The snubber circuit
    4) the 5V rail

    Changing the part to run in synchronous mode (using an external FET instead of a diode) , as well as tuning the inductor value and the snubber circuit values all contributed to helping remove this issue. The instability was caused by a false over-current trigger, and cause the part to go into hiccup mode.