Xenotime, Librarian of Æther 16h ago
Any electronics people know a simple/cheap circuit to precisely measure current but have the measured side be dc isolated (it’s biased at 30V)?

my naïve thought is to just have a good shunt into a like difference circuit with an op amp and resistors and then an ADC can read that

is there a better way to do this?

edit (clarification): some folks picked up on this but I need to measure pretty small currents (<100uA) sensitively so magnetic sensors probably are out. thanks for all the ideas!
Show threadToroidalCore15h ago

@xeno Assuming hall effect sensor isn't what you're looking for, there are special current sense amplifiers meant for high-side shunts that can tolerate higher common mode voltages. Here are a couple:

https://www.ti.com/lit/ds/symlink/ina190.pdf
https://www.ti.com/lit/ds/symlink/amc1301.pdf

Another option is to float an ADC and normal op amp, and then supply it with isolated power from a flyback converter, and use a digital isolator to talk to the ADC.

Show threadXenotime, Librarian of Æther 
@toroidalcore oh this isolation amplifiers could be great options thanks!
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