LM4865: pop issue when switching on and off

My customer keep cb=1uf and reduce ci to 0.39uf, however, the pop issue is still exist.

Hi Ethan,

Can you test by shorting the input side of C11 to GND? This should at least help identifying if we should check the components close to LM4864 or is it related to the connection from the audio source into the AC coupling capacitor.

Have you tried with lower gain? Seems you have 6V/V now, do you need this higher gain or could it be reduced to 2V/V or so?

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

I have shorted C11 to GND, the pop becomes small however the sound become larger.

Lower gain can reduce pop, however, we need 6V/V gain to defeat our competitor, who has large gain and small pop.

Do you have other suggestions? hope to receive your feedback.

BR,

Ethan

Hi Ethan,

What does "sound become larger" means on this case? If C11 is shorted to GND there should be no sound?

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

Sorry, my description is wrong. When I shorted C11 to GND, the pop becomes larger.

Hi Ethan,

Understood, can you try by shorting R23 to BYPASS pin, similar to IN+? Does that reduce the pop?
How is Bypass ramping up and down during power up/down?

Best regards,
-Ivan Salazar
Applications Engineer