EVAL-ADAU1467Z Auxadc

Hello,

Please refer the attached circuit below.

The auxiliary ADC is referenced so that a full-scale input is achieved when the input voltage is equal to AVDD (3.3V), and an input of zero is achieved when the input is connected to ground.

Regards,

Harish

Can I also use 50k ohms?

Hello Lorenzo4711,

Yes, you can. It will use less power so that is good. The negative is that the impedance will be higher when the pot is in the middle of the travel. That makes it more susceptible to noise and RF. You should be able to go up to 100K before you will start getting into trouble with noise. Of course it all depends on the details of your board and what the device does so I am being really general.

The risk here is if there is too much noise on the AUX ADC then the DSP program might start trying to change quickly with the noise and that can cause issues with the audio or the program. There are ways to solve most of these issues with a combination of external filters and software filters. The other issue with a high impedance is that the ADC will take longer to settle to the correct value and may not be super accurate. For things like a volume pot or EQ pot this usually does not matter and is not noticeable. If you are trying to measure a DC voltage accurately then it is an issue.

Dave T