PCM1754: noise issue

Yusuke Mukuno

Expert 7395 points

Part Number: PCM1754

HI expert.

my customer have an issue about noise .

7pin (VOUT_L) is below, it seems some noise that the cycle is around 350ms.

VOUT_L is not connected any resistors or capacitors.

Could you please give me your advice for reason of this noise and your recommendation for solving?

Thanks

over 3 years ago

+1 Paul_Frost over 3 years ago

TI__Guru 53283 points

Hi Mukuno-san,

Does the customer see similar noise on the power supply of the device? Is there some kind of re-synchronization that is occuring on the I2S input signal? For example, is SCK halting momentarily when this happens?

Thanks,

Paul

0 Yusuke Mukuno over 3 years ago in reply to Paul_Frost

TI__Expert 7395 points

Paul-san,

Customer found no bitCLK before output noise.

Does PCM1754 have the output voltage drop if bitCLK don't input.

Thanks

Muk

+1 Paul_Frost over 3 years ago in reply to Yusuke Mukuno

TI__Guru 53283 points

Hi Mukuno-san,

If the BCK signal is halted then the delta-sigma modulator will also halt. That can result in these glitches and they could be audible. I highly recommend the customer avoid halting the BCK, or any of the I2S inputs.

Thanks,

Paul

0 Yusuke Mukuno over 3 years ago in reply to Paul_Frost

TI__Expert 7395 points

Paul-san,

Thank you for your answer!

Muk

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PCM1754: noise issue