INA260: Lowest Measured Current?

Art,

This amount of current is not achievable with this device. The reason is that the internal shunt resistor is a fixed 2mΩ, and is made for sensing more broad current ranges. This range will not generate enough current over the inputs to be able to be differentiated well from the input offset which is a worst case 5mA. This offset comprises nearly a third of your measurement, which means that error on the measurement would be >30% error at the lower end. Also, due to the way the device is configured, the smallest LSB size is 1.25mA, so this would be the smallest value that you could differentiate by in the range. 

A much better choice here would be the new INA229, since it has lower bias currents for small measurements such as this. It is an external shunt device though, so you will need to choose an appropriate shunt. You could also look at our analog devices for options. I would start with the INA190.

Art,

I did mean the INA229 here. The automotive version and industrial version of this device are due out at the end of the year. There are preproduction samples of the automotive version (Q1) of the device available now. 

If you need something that is fully released as of today, INA226 might work here as well, as its step size is much more appropriate to the range you are looking to measure.