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Using external spdif tranceivers with ADAU1452

Question asked by chuckwin on Dec 1, 2014
Latest reply on Apr 8, 2015 by chuckwin



My questions pertains to clock connections on the ADAU1452 when using external spdif transceivers.


My design requires 2 spdif  inputs and outputs to be processed by the ADAU1452.


I have elected to use 2 WM8804 Wolfson transceivers which provide I2S output, so no need to use dsp's onboard spdif I/O. For the moment I am assuming 44.1/48kHz everywhere.


The dsp is using a 12.288MHz crystal, with XTALOUT pin going into an 8-output clock buffer. I am clocking the spdif ICs from the clock buffer, so everything is synchronized to crystal.


The I2S out of each spdif IC goes into its own SDATA_IN on the dsp. The dsp will then slave from BCLK/LRCLK of the spdif IC.


Question is, to what clock domain do I connect the output side of the dsp when sending its SDAT_OUT  back to the spdif IC? I presume it needs to clock from the same source. So is it OK to connect the input-side clock domain on the dsp to the output-side clock domain?


Would you advise buffering BCLK and LRCLK from the spdif IC so that each clock domain on the dsp is driven form it's own low-z source?


Thanks for any advice you can offer me.