PGA2505 "POPS"

Hello,
With zero crossing detection enabled, the amount of audible clicks should be minimized. My first debugging suggestion is to toggle the zero crossing detection bit while changing gain and see how the problem is affected. It should get worse the the zero crossing detection feature disabled. If it does not, verify that the zero crossing detection feature is being properly configured (setting bit 10 in the serial word).

Also, is your microphone being AC coupled into the PGA2505 through coupling capacitors? A more detailed circuit schematic will help us with the debugging process.

Thanks for your reply. Following your suggestion, I debugged my circuit. But it doesn't work and I am sure that the zero crossing detection is enabled. I can see the SDO and SDI data of PAG2505 by oscilloscope. My circiut schematic is the same as TI reference design.

They are almost the same. One is 0.651V and the other is 0.650V.

I find a strange thing that the voltage of Vin+ is the same as Vin- at the beginning of power up(both are almost -0.65V), but a few moment later the voltage of Vin+ increases continuously while the voltage of Vin- decreases. At the last the Vin+ will be 5V and Vin- will be -5V. Why?
Whenever the Vin is floating or connected to Mic, the results are the same.

This is my schematic.

This is my schematic.

Thank you for your suggestion. The Vin DC offset problem could be solved by enabling the CM servo. And the "pops" was solved by removing the schottky rectifier(SS12) D35, D36, D37 and D38. Maybe it's because that the schottky rectifier's reverse current is too large(0.5mA).

Thank you for giving an update on this, that is very useful information for other customers as well!