I've read AN-1271 (Optimizing the ADuCM350 for Impedance Conversion) and from what I understand the following should be done:
- Rcal - Set equal to the lowest expected impedance being measured
- Rtia - Calculate to provide max voltage at minimum impedance
- Ctia - Calculate based on Rtia
My questions are:
- What happens if the device sees a value lower than the expected minimum impedance
- In the 2-Wire example I don't see a call to set the Rtia anywhere, why is this not used?
- Is there any limit how high an impedance can be measured? For instance, with an Rcal of 1k ohm would I have trouble measuring impedances on the order of 10s of k ohms?