How to calculate INA210 VOUT

Ivan,

According to the datasheet, the INA210 has a fixed internal gain of 200 for its internal difference amplifier.

The current through the shunt resistor and load will establish a voltage across the shunt that follows a V=I*R relationship. Therefore Vshunt = I_Shunt x Rshunt = (Vin+ - Vin-).

The difference amplfier will measure this differential voltage (Vshunt) at its two inputs and amplify that differential voltage according to Vout = Vref + (Vin+ - Vin-)*(Gain of INA210). This gain is 200 because R3 and R4 are 5k and R1 and R2 are matched at 1Meg. This gives the gain of 1Meg/5k = 200 for the difference amplifier.

For the INA210, the formula for Vout = (I_Shunt*Rshunt)*(Gain) + Vref where the gain is fixed at 200.

This is a theoretical formula and of course there will be physical limitations of the device and circuit (i.e. output swing to rail, input common mode voltage, offset voltage, gain error, power dissipation in the shunt resistor, noise of power supply, etc). But hopefully this helps you understand the theoretical operation of correlating the output voltage with the input current.

If you have more questions, check out this TINA-TI spice simulation. 6761.Ivan_INA210_10.4.13.TSC

Thanks for your inquiry.