I am using the LMP91200 AFE for 2-electrode pH sensor communication in my project, and I am interfacing it with a PIC controller. While I am receiving some data from the sensor, the issue is that the data is inconsistent. Every time, it gives different values without any change in the pH solution.
I am getting some data from the LMP91200 AFE without connecting the sensor. How can I rectify this issue?

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The output format is analog voltage right?
Remove it from your PIC and monitor the output with oscilloscope to make sure your LMP91200 operates correctly.
Because with the info given we have no idea if the problem is with the electrode or the chip or the communication between the chip and the PIC, or the data processing inside the PIC.
Are you sure you wired everything according to the datasheet? (For some reason I cant upload a photo right now but it is on the third page of the document https://www.ti.com/lit/ds/symlink/l...38477&ref_url=https%3A%2F%2Fwww.google.com%2F ).

 

 

Thanks for the responses.



This is my circuit design

I checked the ADC using the loopback method, and it's working properly. The problem is that I did not connect the sensor to the LMP91200 AFE, yet it is still giving some data through the Vout and Vocm pins."

 

Well that could be reasonable, if the pins are floating they might be picking up induction and process that voltage like probe signal. If you ground the inputs you should have completely dead output. (this is in general, I dont have experience with this particular IC).