Other Parts Discussed in Thread: ADS1261
Hi I have an issue with ADS1261 eval baord. Whenever the PGA is enabled the values read by the ADC are scaled, and dont match their true ampltude. When the PGA is bypassed the ADC reads acceptable values. What would be the cause of this?
I confirmed the input voltage of the ADC with 2 keithley multimeters connected in parallel. I have tested without multimeters and still get the same result. Here are plots from my test. I have also placed the EVM board in an insulated case with a heating pcb attached to the ADC chip with thermal paste. The temp of the ADC was stabilized to 55C according the internal temp sensor. This was done to ensure ambient temperature isnt affecting the readings.
PGA enabled gain 1
PGA enabled gain 128
PGA bypassed (I used smaller voltage steps for this test but its clear the scale factor is much less compared to PGA enabled)
Here is the configuration of the register as im using the TI ADC software to read values
[ADS1261 Register Settings] ID 80 STATUS 01 MODE0 04 MODE1 01 MODE2 00 MODE3 00 REF 15 OFCAL0 00 OFCAL1 00 OFCAL2 00 FSCAL0 00 FSCAL1 00 FSCAL2 40 IMUX FF IMAG 00 RESERVED 00 PGA 80 INPMUX 34 INPBIAS 00
I'm posting here as a last resort to figure out why this issue is happening thanks for reading! Let me know if i missed any details and will fix that right away.
