PCM1791A: sampling frequency setting

Ryo Akashi

Genius 9470 points

Part Number: PCM1791A

Hello experts,

I have question about sampling frequency.

Is sampling frequency decided by input clock to LRCK automatically?

In other words, there is no register for sampling frequency?

Thanks and best regards,

Ryo Akashi

over 5 years ago

0 Paul_Frost over 5 years ago

TI__Guru 56793 points

Hi Akashi,

By default, the device assumes 8x oversampling, which is supported in all fS rates. If you wanted to change the oversample to 16x, then you would have to make sure your fS frequency was <100kHz. There is no required configuration of the device assuming the ratio between LRCK, BCK, and SCK is valid.

Thanks,

Paul

0 Ryo Akashi over 5 years ago in reply to Paul_Frost

TI__Genius 9470 points

Hello Paul-san,

Thank you for your reply.

I understand oversampling ratio should be 8x by default.

If we use 44.1kHz for sampling frequency and oversampling ratio = 8x, we don't need to set any special setting.

In other words, it's ok to just input 44.1kHz clock signal to LRCK.

Is my understanding correct?

Thanks and best regards,

Ryo Akashi

0 Paul_Frost over 5 years ago in reply to Ryo Akashi

TI__Guru 56793 points

Hi Akashi-san,

Your understanding is correct.

Thanks,
Paul

0 Ryo Akashi over 5 years ago in reply to Paul_Frost

TI__Genius 9470 points

Hello Paul-san,

Thank you for your reply. Your comment is helpful.

Let me ask one more question.

If we use fs=44.1kHz and set oversampling rate = 128 times fs by OS[1:0] register, is there any problem?

Thanks and best regards,

Ryo Akashi

0 Paul_Frost over 5 years ago in reply to Ryo Akashi

TI__Guru 56793 points

Hi Akashi-san,

That is fine, but note that in this case SCK must be ≥256×fS.

Thanks,

Paul

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PCM1791A: sampling frequency setting