I have a pH probe which is a high impedance voltage source of which I want to measure in increments of 0.5mV (500uV) with an ADC. This voltage can swing between +/- 1V.
I have chosen this ADC as something that looks suitable for the job: http://docs-europe.electrocomponents.com/webdocs/0d2a/0900766b80d2a9fd.pdf
When placed in 14 bit resolution it should give me 250mV per LSB, more than I need - but that's okay.
Now I'm unsure if I can feed my -1V signal into this ADC, as in all the diagrams it shows VSS tied to GND, not a negative source (like an Op Amp). I expect I can't tie this to a negative source because of the I2C output which would swing negative? <- Just a guess.
Can anyone help me understand if this will just work as described?
Edit: I realize I can bias the pH probe with 1.024V which will put it precisely in the middle of the reference voltage for the Op Amp, but I was hoping to make use of the Gain function of the ADC in certain situations, but if this solve this problem I'm happy to do that.