SPDIF synch issue and pop noise on ADAU1452

dear all,

I am working on an audio application using an ADAU1452. The application concerns the use of SPDIF audio data as well.

The issue I am facing is that I get a huge "pop" noise the very first time the ADAU1452 is initiated, once I connect the SPDIF cable in the optical socket of the evaluation board.

Monitoring the input SPDIF in and SPDIF out of my board it seems that the frequency of the SPDIF data out is locked to about 1.5 MHz after the ADAU1452 is initialised (yellow plot in the attached pictures - the blue plot indicates the SPDIF input). After the cable is connected then the frequency of the data output syncs to about 2.1 MHz, producing a huge pop in the meantime.

All subsequent connections/disconnections of the cable produce no artifacts. Only the first time the SPDIF cable is connected.

I was wondering if that is an ASRC issue. But I have tried different settings with no luck. I am not sure what the root cause might be and how to resolve it.

Any ideas would be helpful.

I am attaching the project file as well for reference.

with best regards,

Dimitris

Audio Signal Processors

adau1452

SigmaDSP Audio Processors