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ADAU1979 PLL and serial audio port clocks

Question asked by jouko.viitanen@wire.fi on Jan 10, 2015
Latest reply on Jun 23, 2017 by Rajeev

Dear Experts,

 

I am planning to use the ADAU1979 in an unorthodox manner. I would like to use asynchronous sources for the serial audio port clocks

(LRCLK, BCLK) and the PLL MCLKIN. Is it possible at all? I can select the sampling frequency freely to be either higher or lower

than the serial port frame frequency.   If it is possible, I understand that with different Fs there will be either missing or duplicate samples, but in this application it does not matter. (A longish explanation why I would like to do this, so not written here).

Another question: there is the facility to mute the output in case of PLL out of lock, but I did not find what the muting actually does at the output of the ADC (i.e. possibly just holds the previous value, or maybe has a Nth order interpolation between the values before and after the out of lock incident, or maybe it works on the analog side?).

I do not have the evaluation board that would easily be used for testing, but maybe somebody can try?

 

Best regards,

Jouko

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