Part Number: ADS131A04
I am looking into simplifying a design to read out photodiode currents using a TIA followed by the ADS131A04. The design I have in mind is the following:
The design would be replicated on all 4 input channels. As you can see, I would be using the ADC with a unipolar 3.7V supply, same for the OpAmp of the TIA. The output of the REFP pin would both be used as reference for the TIA and for the ADC (on the positive pins). This way, the readings are positive (the TIA inverts the signal, and the ADC inverts it back since it's connected to the negative input), and I don't need to generate a negative voltage.
Is this design feasible? I am mostly concerned about the suitability of REFP (with the internal reference being used) as a reference for the TIA and ADC inputs. According to the datasheet, it can source 100uA, while the OpAmp has bias/offset currents in the 10pA range, and the ADC is expected to draw ~18uA per channel (at 4MHz modulation frequency, using equation 5 from the datasheet), for a total of ~75uA. So it seems this should be fine. Am I missing something?
