SBOS956 December 2018 INA240-SEP
For this application, the INA240-SEP measures current in the drive circuitry of a 36-V, 4000-RPM motor.
To demonstrate the performance of the device, the INA240-SEP with a gain of 20 V/V was selected for this design and powered from a 5-V supply.
Using the information in the Adjusting the Output Midpoint With the Reference Pins section, the reference point is set to midscale by splitting the supply with REF1 connected to ground and REF2 connected to supply. This configuration allows for bipolar current measurements. Alternatively, the reference pins can be tied together and driven with an external precision reference.
The current-sensing resistor is sized so that the output of the INA240-SEP is not saturated. A value of 100-mΩ was selected to maintain the analog input within the device limits.