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TPA3244: My PCB is unstable, please advise!

Simon Ashton
Prodigy 20 points
Part Number: TPA3244

Hello,

I created the below PCB. IT is designed as 1x BTL, 2x SE with option to make 2x BTL. When I power it up I hear a hum that intensifies until it cuts out.

Power rails remain stable.
Reset is floating.
Fault pin remains HIGH, even though the sound cuts out.
If I keep reset pulled to GND during power up and then release it (manually) it never makes sound nor passes signal (seems like it doesn't start up).
Disconnected the TPA3244 signal inputs from the buffers. Issue remains the same.

Please see the video here:

Could my choice output inductor cause this problem? They are a generic toroid power inductor - https://lcsc.com/product-detail/Through-Hole-Inductors_Sunltech-Tech-SLT080125T150MTB_C908343.html

Here is my schematic and layout.

Thanks for any help!

(Before someone says it - those are the op-amp and regulator symbols built in to EasyEDA, and while they are horrible I could not bother to draw my own.)

  • 0
    TI__Genius 14250 points

    Hi 

    Can you help confirm the /FAULT and /CLIP_OTW pin, we can check the error report.

    i also suspect the inductor lead to this problem, can you take a try removing the inductor, then confirm the out A, B, C, D directly.

    thanks.

    Jesse

  • 0 in reply to Jesse Ji
    Prodigy 20 points

    I figured it out!

    I have a copper pour on the top and bottom signal layers and that is only connected to the GND plane at the Signal GND point.

    (I know this was stupid, it is my habit from low level low freq. design where the copper pour is only acting as a shied.)

    I now made the copper pour on top and bottom floating and the issue has been fixed.

    So I have a question:

    Is it best to NOT have copper pour on the top and bottom layers next to output traces? Or is it best to have copper pour, but add many vias to GND plane following the traces?

  • 0 in reply to Simon Ashton
    TI__Genius 14250 points

    Hi Simon

    Usually we will have copper pour and add many vias.

    it will be better for EMI and thermal.

    thanks.

    Jesse