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ADAU1361, when Power-On/Off, noise occurs on the HP output

Question asked by Paramecium on Sep 4, 2014
Latest reply on Sep 22, 2014 by Paramecium

Please let me ask you how to suppress the Headphone output noise.

When Power-On/Off sequence on the ADAU1361, noise occurs on the HP output.

Unfortunately I cannot avoid the noise ...

How order should we set the register ? Or should we apply any countermeasures on the hardware ?



1. Power-ON

I set register as following sequence. Then a small noise occurs.

- R22,24 register, Mixer3/4 setting

- R33 register , MONO setting

- R29,30 register ,RHPM RHPM setting


I have checked below. But the noise still appears.

              data sheet ( rev.C ) Page 36

             ( Figure 45. Headphone Output Power-Up Timing )

             > To prevent pops when turning on the headphone outputs, the

             > user must wait at least 4 ms to unmute these outputs after

             > enabling the headphone output with the HPMODE bit.


If I wait several seconds after Mixer3/4 setting, I can avoid the noise, I confirmed.

But the wait time is too long to implement on our system...


2. Power off.

Pop noise occurs.

I have checked and operate as written in below.

But I cannot avoid the noise ...


             data sheet ( rev.C ) Page 36

             ( Figure 46. Headphone Output Power-Down Timing )


If you have any ideas,

would you please let me know ?