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BQ25723: Sharp beeping sound from input capacitor

Xavier
Prodigy 140 points
Part Number: BQ25723

Tool/software:

Hi all,

My circuit uses a 20V power input and the input capacitor emits a sharp beep when the input power is 20-45W.

I used five 10uf/25V capacitors.

After reducing to 1 capacitor, the beeping sound remains.

What can I do to get rid of this beeping sound once and for all?

Best Regards,

Xavier

  • 0
    TI__Mastermind 32745 points

    Hi, Xavier,

    Could you provide a waveform showing the switch node when the noise is observed? For example, VIN, VSYS, VSW1 and VSW2, also list the operation conditions. 

    Regards,

    Tiger

  • 0 in reply to Tiger Zhou
    Prodigy 140 points

    Hi,Tiger,

    I'm not in the office area right now, so I may send the waveform two days late, please understand!

    I can add the phenomenon that after I remove all 5 MLCCs and re-solder a 3.3uF/35V tantalum capacitor, the noise will disappear.

    But this doesn't seem to be in line with the recommended design of the BQ25723, I'd like to ask if there are any pitfalls in using tantalum capacitors on the inputs, if not maybe I can accept this change.

    Best Regards,

    Xavier

  • +1 in reply to Xavier
    TI__Mastermind 32745 points

    Hi, Xavier,

    The ceramic caps may emit audible noise under excitation. I have seen customers using tantalum caps for input capacitors. Just pay attention to the ripple current spec of the tantalum cap. Other than this, I think this should be a viable solution.

    Regards,

  • 0 in reply to Tiger Zhou
    Prodigy 140 points

    Hi,Tiger,

    I'll use tantalum caps for input capacitors.

    Thanks,

    Xavier