PCM1865 - pop noise in case of Analog PGA change

Hirotaka Matsumoto

Other Parts Discussed in Thread: PCM1865

Hi all

Would you mind if we ask PCM1865?
Could you refer to the following file?
20161004_PCM1865_PopNoise.pdf

When Analog Gain changed, it occurs pop noise.
We would like to prevent from pop noise, could you give us some advice?

Kind regards,

Hirotaka Matsumoto

over 9 years ago

0 Luis Fernando Rodriguez S. over 9 years ago

TI__Guru* 84915 points

Matsumoto-san,

I would recommend to increase the gain in 0.5dB steps. As mentioned in datasheet (page 22), care should be taken when changin gain levels in digital PGA.

Please let me know if the problem persists.

Best regards,
Luis Fernando Rodríguez S.

0 Hirotaka Matsumoto over 9 years ago in reply to Luis Fernando Rodriguez S.

Guru 27585 points

Luis san

Thank you for your reply always.
We tested like as the following file;
20161006_PCM1865_PopNoise.pdf

The problem presists.
So, could you give us some comment?

Kind regards,

Hirotaka Matsumoto

0 Luis Fernando Rodriguez S. over 9 years ago in reply to Hirotaka Matsumoto

TI__Guru* 84915 points

Matsumoto-san,

Could you test changing the analog gain in the minimal steps? The tests that you shared configure the gain from 0dB to 24dB. I would recommend to modify this analog gain in the minimal steps. This should reduce the pop noise.

Best regards,
Luis Fernando Rodríguez S.

0 Hirotaka Matsumoto over 9 years ago in reply to Luis Fernando Rodriguez S.

Guru 27585 points

Luis san

Thank you for your reply always.
Please refer to the following file.
20161007_PCM1865_PopNoise.pdf

We would like to reduce pop-noise in case of gain changing.
In case of AGMF setting, in generally, it contains 0.5dB step, right?

Kind regards,

Hirotaka Matsumoto

0 Luis Fernando Rodriguez S. over 9 years ago in reply to Hirotaka Matsumoto

TI__Guru* 84915 points

Matsumoto-san,

The last captures of the document that you shared show a normal behavior. The PCM1865 should have an input to avoid pops. I would recommend to enable smooth change (zero crossing function) to reduce pops.

By other hand, the automatic clipping suppression have the ability to automatically lower the gain in 0.5dB steps under clipping conditions.

Best regards,
Luis Fernando Rodríguez S.

0 Hirotaka Matsumoto over 9 years ago in reply to Luis Fernando Rodriguez S.

Guru 27585 points

Lusi san

Thank you for your reply always.
I would recommend to enable smooth change (zero crossing function) to reduce pops.
->Yes, we encouraged our customer to use enable smooth change, and they use it already.

At the moment, we got that this a normal behavior.

Kind regards,

Hirotaka Matsumoto

0 Luis Fernando Rodriguez S. over 9 years ago in reply to Hirotaka Matsumoto

TI__Guru* 84915 points

Matsumoto-san,

Glad to read that you have a normal behavior. Please let me know if you require more information about this.

Best regards,
Luis Fernando Rodríguez S.

Audio

Audio forum

PCM1865 - pop noise in case of Analog PGA change