AC/DC Current shunt 0-30A with 250V common mode

[Jester]

Looking to improve a current measurement circuit that uses a LEM LTS 25-NP hall effect sensor. The dc offset of this particular device is not great and moves around quite a bit. With a x10 post gain stage and software calibration I can resolve to about 1mA however day to day dc offset moves around by 10-20mA. I'm considering adding auto zero feature to the software, however I would prefer to just upgrade the circuit to something inherently more stable.

I have looked at for example the INA186Ax series of Bidirectional current sense amplifiers and these would almost certainly yield better results and be less costly, the problem is that in some situations the circuit sourcing the current could have common mode voltage of up to 250Vrms. 

Any suggestions?

[Wolfram]

Is the common mode voltage a static offset, or is there an AC component to it? If so, what sort of slew rates are expected?

Isolated delta-sigma converters for current shunt sensing might be an option, if you can live with a delta sigma bitstream rather than an analog output signal. I've used the AMC1106 with success in the past.

[CoteRotie]

Or if you want to stay analog you could look at the AMC3302 from TI.  It has isolation AND an isolated DC-DC converter to power the input side of the amplifier.

[Phoenix]

Or if you want to stay analog you could look at the AMC3302 from TI.  It has isolation AND an isolated DC-DC converter to power the input side of the amplifier.

I'm using an AMC1300B in a product I'm developing (inverter current measurement) for current shunts and I'm quite happy with it. the AMC3302 is similar and with built in isolated power supply.

[jbb]

LEM make some newer devices - maybe the CKSR? range would help.