I have some questions regarding the ADuCM355. We want to use this device for several measurements. That’s why we will use the MUX for the TIA.
The -5/+15% accuracy refers to the initial accuracy of the resistor to its expected value. For example, if you select the 10kohm setting, the worst case values at 25C across any part you receive is 9.5K to 11.5K.
The +/- 0.6% gain mismatch is the error introduced if you change the TIA gain resistor value. So, if you are using the 10K resistor and increase to the 20K resistor, the difference in measurement is +/-0.6% (worst case) - typically its +/-0.2%.
But note, we provide calibration routines that allow you eliminate these error sources.by generating a calibration current across the external calibration resistor (RCAL).