CurrentRanger w/ isolation amplifier

[jamie]

I'm planning to feed the CurrentRanger analog output into an isolation amplifier (AMC0302R-Q1), which has a ~6.3 k ohm dynamic input impedance due to a switched-cap front end.

Can the CurrentRanger analog output drive a load in that range without introducing significant measurement error or other issues? Thanks.

[Felix]

Not sure how you're trying to use the CR with that amp but the input range of that part is +/- 50mV.
The CR can output up to 3.3V depending on the current seen at the input.
The CR output is not really designed to drive any load whatsoever, however since the input impedance of your isolation amp is high it should be OK. However I can't speak to the noise figures since I don't know enough and even then an experiment is needed to verify the theory.
You will have to worry about powering your amp from both isolated sides.
Since this is experimental I hope you know what you are doing and wish you good luck :-)

[jamie]

Thanks, Felix.

I'm trying to design an isolater so I can use the CR with my Saleae MSO while also measuring voltage via another channel. This scope only has single-ended inputs so the two ideas I had was a) trying to read and decode the serial output from CR using the Saleae's LA channels or b) figure out a way to eliminate the ground loop on the analog inputs. I'm already using all of the LA channels in my test fixture and I'd probably have to use a MCU to issue an "Ok" command anyhow. So Option B seems like the simplest option. I'm aware that it'll limit me to 50 mA, but that's fine for my particular application. (TI also makes the AMC0300R-Q1 with a 250 mA input range).

[Felix]

jamie,
Which serial output are you referring to?
There is USB serial output as explained here. There is also the "BT serial header" which will only output if it detects an HC06 bluetooth module but you can recompile to force output I guess.
For isolating the input you could just use a floating power supply (ex battery) to power your PSU.
With USB you could simply use a USB isolator.
So not sure if it's still worth the effort to build an isolator.