External ADC/DAC on ADAU1701 - minimum required components

SigmaDSP & SigmaStudio Thomas73 Aug 31, 2015 00:00 2 replies Original on forum ↗

Thomas73 Question

Aug 31, 2015 00:00

I'm wondering if I want use external ADC and DAC on ADAU1710, is it possible just keep the pins for FILTA, FILTD, CM, ADC_RES and ADC itself unused - or have they other function what it makes necessary to connect the parts as in the reference schematic? How about the pins itself, just leave unconnected or tie to ground/supply?

Thanks!

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DaveThib Reply

Sep 3, 2015 00:00

Hello Thomas,

Are you planning on using the AUX ADCs? If you are not planning on using those then do the following:

FILTA: NC (NC= No Connect)

FILTD: NC

CM: NC

ADC_RES: NC

If you are not planning on using any analog then Power down all analog in
software using register 0x0822.

ADC inputs can be tied to AGND as long as the internal voltage reference is turned off. If it remains on then tie the ADCs to CM.

DAC outputs left with no connect.

The Auxiliary ADC and power control register also allows you to power down the voltage reference for the analog section. What I am not sure about is if the AUX ADCs will require this voltage and I think it will. This will require some research to find the answer.

You will still need to supply AVDD to the part, and have bypass caps on it, even though you power down all the analog.