This diagram is of a motor using two low-side current shunt resistors for the control loop. The primary design criteria in selecting a low-side current sense amp are gain bandwidth and slew rate. Low-side currents are switching very fast and have very small duty cycles. Therefore, the low-side sense amplifier must have a high gain bandwidth, typically on the order of at least 20mHz, and a fast slew rate on the order of at least 10V/µS in order to accurately capture the current measurements. Rail-to-rail input and output support improves the accuracy of the measurement by providing a greater input and output range to scale the reading with. Low DC offset and low offset drift over temperature are also desirable features to consider when selecting a current sense amp. DC offset and drift can be compensated for in software, but for the best performance it is important to select an amp with low DC offset and drift.