LP5569: LP5569 PWM noise

Kazuki Kuramochi

Part Number: LP5569

Hello expert,

Our customer have question for LP5569.
This device datasheet said there isn't risk regarding audio band with due to PWM frequency is higher than 20kHz.
However, they need to use long trace for LED line there for they worry about noise radiation issue.

Then, we are thinking to add passive filter on the between LEDx pin and LED.
Is this workaround acceptable?

Also please let me know if there is other way of resolving noise radiation issue.

Best regards,
Kazuki Kuramochi

over 4 years ago

0 Monet Xu over 4 years ago

TI__Genius 9255 points

Hi Kazuki,

A small capacitance is suggested to put closed to the OUTx pins and please try to minimize the loop area.

Best Regard

Monet Xu

0 Kazuki Kuramochi over 4 years ago in reply to Monet Xu

TI__Genius 11275 points

Hi Monet,

Thank you for your swift reply.

Is there recommend capacitance on OUTx pin to GND for improving noise performance?
Also, is there maximum capacitance that we can put on this?

Best regards,
Kazuki Kuramochi

0 Monet Xu over 4 years ago in reply to Kazuki Kuramochi

TI__Genius 9255 points

Hi Kazuki,

The specific value of the capacitance depends on your actual circuit. You can have several tries to confirm the optimal capacitance value.

Best Regard

Monet Xu

Power management

Power management forum

LP5569: LP5569 PWM noise