Hello, we try to develop a pH measurement unit with the LMP91200.
First we bought the Sensor AFE Evaluation Board for pH sensors and tested it with the SPIO4- Board. It worked fine. But when we configured the LMP91200 with differential output the software did not allow that. OK on EVAL- Board the ADC did not support it.
As we destroyed the ADC we replaced it with the ADC141S626 that supported differential output. Then we use the EVAL- Board as stand alone. But in differential mode the VCM- Pin and the VOCM- Pin began to swing with 100mV Peak to Peak.
(Maybe mistakes from replacing the DAC)
New PCB... but the problem is still there.
Is that problem known? What can we do?