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First value read by ADC can vary from chip to chip?

Question asked by J3627 on Jul 23, 2013
Latest reply on Jul 24, 2013 by BrettG

I'm reading an Aux ADC and then holding the minimum value with a slow release time.  This has only been a problem on 1 out of 7 prototypes, but on that one, the value is held much lower than it should be.  If I reset the DSP, it then behaves normally.  So I thought it might be because the ADC voltage doesn't settle before the DSP turns on, but I've tried increasing the time for the DSP RESET pin to orders of magnitude longer than the ADC pin voltage takes to settle, but it still doesn't help.  So maybe the first value read by the ADC is wrong?  Any ideas on how to work around this?  Feed the hold block a fake value for the first few milliseconds after boot or something?  It's a self-boot ADAU1702.

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