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TPS92512HV: The Inductor howl issue

Zhang Liang
Genius 4125 points
Part Number: TPS92512HV

Tool/software:

Hi,

We use the TPS92512HV for our LED driver, and now, the Inductor howl issue is happen when the output current is larger than 0.7A, our input voltage is 12V and output current is 2.5A max.

Pleaes refer to below schematic diagram and provide your comment if there are any error, thanks.

  • 0
    TI__Mastermind 23150 points

    Hi Liang,

    When will the inductor noise happen? Does the noise only exist when you are doing PWM dimming through the PDIM pin? Or does the noise exist even when you set the PDIM pin to constant high?

    Best Regards,

    Steven

  • 0 in reply to Steven Li
    Genius 4125 points

    Hi Steven,

    Our test cycle is 20-100us, the high voltage time is 5-20us, the Inductor howl is happened, we reduce the IADJ and there are some improved;

    but the output current will be decreased, there are no noise exist when set the PDIM pin to constant high, thanks.

  • 0 in reply to Zhang Liang
    TI__Mastermind 23150 points

    Hi Liang,

    It looks like this is caused by the PWM dimming. However, for cycle = 20us, the dimming frequency is 50kHz, which is out of the audible range of human ears. Do you still hear the noise from the inductor at this condition?

    Best Regards,

    Steven

  • 0 in reply to Steven Li
    Genius 4125 points

    Hi Steven,

    We use the 20-100us cycle maybe exceeding the range of the dimming frequency range 100Hz-1KHz, and the 200Hz has no noise,

    so we will update the cycle to match the dimming frequcecy and test again, thanks for your kindly help.

  • 0 in reply to Zhang Liang
    TI__Mastermind 23150 points

    Hi Liang,

    Sorry but I do not clearly get your meaning.

    Anyway, if you want to reduce the inductor noise caused by PWM dimming, then increasing the PWM dimming frequency to a value that is out of audible range (>20kHz) is a way to solve this problem. Changing the inductor to a better / quieter type may help, but it only alleviates the noise and does not remove the root cause.

    Best Regards,

    Steven