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UCC2897A: power supply for audio system has noise

Vickers
Intellectual 980 points
Part Number: UCC2897A


Hello,

Schematic:

Measured waveform,Channle 1 is Mos drain waveform.Channle 3 is 12V output current waveform.

Is the current waveform normal?

Now we use this chip to power our system, and our audio is going to be noisy.

Instead of using this chip for power, we plug the adjustable power directly into the back 12V to power our system, and the audio noise disappears.

Now we suspect this power supply.

  • 0
    TI__Genius 13660 points
    Hello,

    Thank you for your question, I have asked one of my colleagues to answer this question.

    Regards
    Teng
  • 0 in reply to Teng Feng
    TI__Mastermind 34465 points
    Hello user5178406,
    It look like there is a 25kHz or so oscillation on the 12V output.
    I can see that your circuit does not have the cap C19 fitted in the feedback circuit.
    If you fit something like a 1nF part here you should be able to get a low frequency pole that will stabilize the loop.
    This should help with the audio noise. I think your system is just unstable .
    Hope this helps
    Regards
    John