I'm currently working on a project that involves using the AD7771 delta-sigma ADC. While the SPI interface seems to be functioning properly, I'm encountering an issue with the received data. Upon measuring the voltage output on the REF_OUT pin, I noticed it is at -1.65V, which matches the AVSS voltage level. I have thoroughly checked all the power supplies and couldn't identify any apparent problems.
I have an external reference (2.5V), but it's referenced to the GND, so i can't use it.
I would greatly appreciate any assistance.
Thank you in advance for your support.