INA186-Q1: Shunt resistor

Hey Timur,

Thank you for your question.

I am concerned that this would be a problem depending on the inductance of the 0.5m cables. The device operates with the very fast charging and discharging of internal capacitors, so input inductance could translate into high-impedance traces and thus increase the device's offset, although it is possible the offset increase will be insignificant (tens of uV) to your design.

Is this in-line current sensing? 

I would recommend setting everything up and biasing the REF pin to mid-supply (so if VS = 5V, then VREF = 2.5V), then accurately record the VOUT voltage with no motor current and the inputs tied to GND of motor voltage supply rail. Then short the input pins (IN+ and IN-) directly at the device (so remove the long cables) and connect input to GND of motor voltage. Record VOUT here.

The difference in the VOUT measurements should show the offset induced by the cable's inductance.

I would recommend placing an input differential capacitor right at the IN+ and IN- pins. This should help correct for the offset by acting as a decoupling capacitor. The input cap should provide charge for the internal switching capacitors. The capacitor should be higher than 1nF. The drawback with this is now you have a LCL differential input filter and if you are trying to measure fast current transients, then this filter will dampen the Vshunt signal and slow down response time.

Hope this helps.

Sincerely,

Peter