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Original question:

LM5166: The output voltage tolerance issue

TPS23730: The Inductive howling for the TPS23730

Zhang Liang
Expert 2455 points
Part Number: TPS23730

Hi,

We use the TPS23730 for the POE PD, and the output is 12V/5A;

Now, there are about 50% boards has the howling issue when the power on, and we test the output power is 7W( Normal is 3W) when light load mode;

and we consider it is resonance for the Inductive;

So please kindly review the schematic diagram and advise how to measure the waveform to comfirm which device is the main issue, thanks.

LH-AIBOX PWR V102.pdf

  • 0
    TI__Intellectual 1451 points

    Hi Zhang, 

    You can measure the current waveforms of your devices to see which may be causing an issue.

    With the howling issue you may consider testing different switching frequencies to find the frequency at which the inductor does not howl.
    There may be a specific frequency range at which the issue appears.
    In addition you can try different inductors and your ceramic conductors to see if any of these components are the issue.

    Best,

    Sarah

  • 0 in reply to Sarah Lao
    Expert 2455 points

    Hi,

    Please kindly which ceramic conductors is the more possible because there are many device, thanks.

  • 0 in reply to Zhang Liang
    TI__Intellectual 1451 points

    Hi Zhang,

    Are you able to audibly locate the specific source of the howling noise to confirm?
    Is the sound louder from the inductor, input capacitors, or output capacitors?

    Are you able to replace the output capacitors (C1, C2, C3) with electrolytic capacitors if possible, and see if the sound will still occur?

    Thanks,
    Sarah