PCM1753: Pop noise issue during power-up

Hi Kato-san,

You have a few threads open about this topic, so the answers will probably be similar in each one. 

The PCM175x is an older device and it does not have much clock error protection circuitry.  There is a risk of a pop noise whenever the delta-sigma modulator starts or stops, or when there is a clock error.  Basically, when the DSM is switching, there is no sudden DC change (besides those desired from the digital input source), but if there is a clock error, the DSM stops.  During a stop, the ~7 current segments go to a DC state, that can be different than the VCOM voltage.  This abrupt stop can sound like a pop or glitch if the magnitude is large enough.  

The only way to avoid this is to implement an external mute functionality that can be asserted when there is a clock error, but that error detection would need to come from the I2S source rather than the PCM175x.

Thanks,

Paul