INA240: Current Measurement Range

Michael,

The measurement range for the INA240 is not fixed, as this is not a property of the amplifier, but of the chosen shunt resistor and gain variant of the device. Your choice of shunt will affect the full scale range, with the tradeoffs being a thermal challenge at the full scale range end of the curve, and an accuracy challenge at the bottom of the curve as offset and bias current effects begin to dominate the measurement. For example, if I chose the 20V/V A1 variant, and a 100mΩ shunt, in the ideal case, I would be able to measure up to 2.5A before I saturate the output (.1*2.5*20 = 5V output). However, if I change my shunt to a 10mΩ shunt, I can now measure a range up to 25A according to the same equation. However, the thermal and accuracy outcomes I explain above are very different in each of these scenarios, so a design decision needs to be made to find an optimal operation point. 

On your question regarding sensitivity, the INA240 does not have a sensitivity in mV/A, but rather a gain in V/V. This is because the device is looking for a sense voltage across its input pins which it will then gain by the chosen value to determine the output voltage. To be able to determine a sensitivity level, a shunt value needs to be chosen, which is up to the designer. The output voltage is given by the formula VOUT = R_SHUNT*I_LOAD*GAIN, so I believe if you wanted to create an expression for sensitivity, you would simply need to multiply the chosen gain by the chosen value of shunt resistor. 

Thanks for the info.