LM3410XMFLEDEV: lm3410xmf

Hello,

I am not sure I understand with the information given. Do you mean it hums during normal steady state operation? Or is this humming during PWM dimming? Are you just using the EVM and it is making noise?

If it is humming during PWM dimming you may want to search the forum. It's a common issue and generally requires experimenting with different inductors (if it is the inductor) or different capacitor case sizes and number of caps (if it is the capacitors).

Regards,

Clint

We are not using EVM, we have our custom board. Please see the attach schematics.

We are having humming sound and it increase when we increase the brightness of the LCD i.e. increase in PWN duty cycle.

As of now we have tried to replace the ceramic capacitors with Tantalum and inductor to 8.2uH but it didn't helped. We also decreased the PWM frequency from 10khz to 1khz but not seeing significant improvement.

It seems inductor is the culprit here. Can you suggest more troubleshooting method?

Hi Clint

We tried connecting the dim pin to input voltage and noise went away and this was suggested by TI person. but when we use PWM we are still seeing the noise.

Can u suggest a solution. We tried with 1 Khz frequency. Will it help if we reduce the frequency.