I thought of using an external ADC and then optoisolate on the digital side, however the ADC then needs to be powered from the system that is being measured which is not a good idea.Any other ideas?
Isolated ADCs are available, such as MAX14001.They contain their own DC-DC converter, which solves your problem about powering.
The IL300 is an analog optocoupler.
Hi,What is wrong with switched capacitor method?Tom...
The IL300 is an analog optocoupler