RE: Designing output isolated 4-wire sensor transmitters

AP — Fri, 18 Dec 2020 06:40:51 GMT

Hello,

I'm wondering about figures 1 & 2. Isn't there an issue regarding the ADC input voltage levels? The voltage accross the resistor must fit into the ADCs differential input voltage range, OK. But what about the maximum allowed voltage levels on the ADC inputs relative to the ADC ground (typically earth ground in typical non-isolated SMPS based DC systems)? E.g. what about the ADC input common mode voltage rating (referenced to ADC ground)? The resistor voltage (the IN+ and IN- voltage) seems to be floating relative to the ADC ground.

Thanks,