Why am I hearing a humming sound from my LED array?

Hi,

I have been working on this consumer electronics project which uses LT3599 LED driver to control a 4 channel LED ring.

Here, I have used True colour PWM led brightness control & the problem is that, while the LED ring is on, I could hear small humming sound from the LED ring itself.

What could be causing this humming sound?

Is there any remedy to prevent or to reduce this effect?

Except for some changes in the current control resistors, the LED driver circuit is just like the one in the datasheet.

Thanks & Regards,

Hari

  • 0
    •  Analog Employees 
    on Mar 27, 2018 9:26 PM

    Here, I have used True colour PWM led brightness control & the problem is that, while the LED ring is on, I could hear small humming sound from the LED ring itself.

    What could be causing this humming sound?

    The buzzing sound that you are hearing is due to the piezoelectric effect of the multi-layer ceramic capacitors used on the LED driver circuit. These ceramic capacitors can deform under bias, and cause the PCB to flex and vibrate.

    Is there any remedy to prevent or to reduce this effect?

    Board layout is critical for reducing any piezoelectric effect. Without altering the board layout, you could adjust the PWM dimming frequency so that it is outside of the audible range (above 20kHz), but this will limit the maximum achievable dimming ratio.