Resistive loading at the input pin (IN+ and IN-) and bias or reference pins (REF) of current sense amplifiers (CSA) can create significant error (e_EXT) in the output measurement; however, this error can be calculated and managed to acceptable levels for low-accuracy, low-cost, or small form factor applications.

In this guide, CSAs with resistance at input and reference pins are designed, and tested over temperature. Two types of devices are tested. One device is a standard linear CSA (INA185) and the other device is a capacitively-coupled, high-input impedance CSA (INA191). Both devices are tested with and without input resistance over temperature to determine and verify the error generated solely from the input resistance.