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LM51772: frequency sound issue

GARETH OU
Guru 11665 points
Part Number: LM51772


Tool/software:

Hi 

When testing LM51772, it was found that the 65W PD DC-DC set has a fixed frequency sound when VOUT is 20V and VIN is about 11.5V~12V. At this time, the measured VIN voltage ripple will be slightly larger. Which part of the circuit can be adjusted to eliminate this [sound] problem?

Thanks you

  • 0
    TI__Guru 61011 points

    Hi Gareth,

    i would be good to first identify the source of the sound.

    There two options:

    - inductor 

    - input or output caps

    For the first step can you remove the inductor and connect it with short flexible wires.

    If the sound is gone we know it was the inductor.

    Best regards,

     Stefan