TPS92513: PWM dimming whistling sound

Lucian Dale

Part Number: TPS92513

A single TPS92513 circuit coil at 100Hz or 200Hz make like a cicada. At 1kHz it is a lot of whistling. Vin=24V , Vled=11V, LED current = 272mA.

How can audio noise be canceled?

Thank you,

Luci

over 7 years ago

0 Irwin Nederbragt over 7 years ago

TI__Mastermind 28655 points

Hello,

This is a common issue with PWM dimming. Inductors, ceramic capacitors and other components can emit noise from the square wave of current. You can try a different inductor or a potting compound/epoxy.

Regards,

0 Lucian Dale over 7 years ago in reply to Irwin Nederbragt

Prodigy 20 points

Hello,

Can I increase the dimming frequency to 22kHz? The specifications, not restrictive, are "The dimming frequency range is 100 Hz to 1 kHz".

Thank you!

0 Irwin Nederbragt over 7 years ago in reply to Lucian Dale

TI__Mastermind 28655 points

Hello Lucian,

Increasing the PWM freqeuncy to 22 KHz will lose linearity. The inductor has to ramp the current up and down when the PWM pulse goes high and low. You can try it but it is out of the datasheet specified range.

Regards,

0 franziskus over 7 years ago in reply to Irwin Nederbragt

TI__Expert 8249 points

Irwin,

do we have any recommendation regarding inductors/special coils to reduce audible noise in these applications?
How do we handle this on our EVM/TI Designs?

Thanks,
Franziskus

0 Irwin Nederbragt over 7 years ago in reply to franziskus

TI__Mastermind 28655 points

Hello,

It's really just trying several different inductors. It will vary from design to design due to LED current, di/dt, dv/dt. Layout can also affect noise (how the board is shaped, size, etc. Also, applying potting or glue can help with this also.

Regards,

Power management

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TPS92513: PWM dimming whistling sound