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TPS61178: TPS61178 electrical noise

Marx Pan
Intellectual 325 points
Part Number: TPS61178


Dear TI Team,

We are using the TPS61178 to generate a 5 V output and have observed audible electrical noise coming from the device and its surrounding circuitry. Could you share any experience, guidance, or recommended mitigation techniques for this issue?

Below is our sch and TI reviewed it.

20251027.jpg

 

Thank you for your assistance.

  • 0
    Intellectual 325 points

    We did belw check:

    1.Unstuff output MLCC(C2402,C2403,C2409~C2411):electrical noise still existed.

    2.Unstuff input MLCC(C2400,C2401):electrical noise still existed.

    3.L2401:1uH->2.2uH, electrical noise still existed.

    4.R2405(FREQ/SYNC pin):249K->110K,electrical noise still existed.

    Thank you.

  • 0 in reply to Marx Pan
    TI__Genius 13195 points

    Hi Marx,

    Audible electrical noise usually comes from power inductor or mlcc capacitor, if the ripple frequency on these inductor or capacitors is within audio band (20Hz ~ 20kHz), there may be audible noise. Usually it will happen at light load because in light load our device operates in PFM mode, device reduces the switching losses and improves efficiency at the light load condition by reducing the average switching frequency, so the frequency may falls into the audio band.

    You can check the SW node or VOUT ripple waveforms to check if the frequency is audio frequency or not.

    If that, using the FPWM (TPS611781) could solve, in the forced PWM mode, the TPS611781 keeps the switching frequency being constant for the whole load
    range.

    Regards,

    Nathan