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TPA3112D1: Problem with Shutdown and Vcc over 17V

Part Number: TPA3112D1

I have an issue with this IC. I placed a switch to shutdown the device manually, but the devices goes to DC FAULT each time I activate the shutdown switch AND the supply voltage is over 17V. If I lower to, lets say, 15V and cycle the shutdown switch, the error disappears and I'm free to increase the VCC to 24V and everything works fine, but in this case if I again use the shutdown, again the IC gos to DC fault. I'm not able to imagine what is going on.

Any help will be appreciated.

Julio Walter

  • Hi Julio,

    Here are the recommended debugging steps:

    1. Capture the waveforms: SD, Fault, PWM. Figure out which stage happens Fault and whether it is a true DC fault.
    2. Short both two input to GND with DC decoupling cap, then repeat toggle SD at high voltage.

    Rdgs,

    Matthew

  • Dear Matthew

    I did what you recommended and I captured the relevant waveform, which I include in this message. The channels are distributed as follows

    Yellow->Shutdown switch

    Blue->FAULT

    Magenta & Green->OutN & OutP

    With PVcc in 17V or less the FAULT never goes on, but if I increase it to 18 or more, no matter if the inputs are shorted or not, the IC turns on the FAULT, which, by the way, turns off whenever the SD is cycled. The only difference I was able to note is that 15ms after the shutdown is released, the outputs peaks higher with 18V than with 17V.

    Any suggestions...?

    Best Regards

    Julio

     17V SD Engage

     17V SD Release

     18V SD Engage

     18V SD Release

  • hello Julio,

    with INP and INN short to GND, when PVDD >17V, you also monitor DC fault trigger? how you judge it is DC fault?

    regards
    Linda
  • Dear Linda.

    I assume that is a DC FAULT because in the IC data sheet says is the only condition that is not cleared when the shutdown is operated and that needs a power recycle to be cleared

    As all the faults are ORed together, I was not able to separate it in any other way...

    Best Regards

    Julio Walter

  • hello Julio,

    it looks not like DC fault trigger. could you please share our team members your whole schematic? and did you play with our EVM or your designed board? you can email your content to derek-gong@ti.com. he will follow up analysis with you.

    regards
    Linda
  •  Dear Linda

    The schematic is below and I don't have the EVM... It is expensive for me. I'll send this communication to Derek Gong also.

    Thanks a lot for your help

    Regards

    Julio Walter

  • hello, Julio,

    could you please follow EVM user guide: www.ti.com/.../slou272a.pdf page5 to add switcher.
    you setup could make GND noisy and make impact for single ended input.

    Regards
    Linda