The INA310x measures differential voltage developed by current flowing through a current-shunt resistor. Figure 7-5 shows the circuit with INA310x used for turning off the high-side switch in case of overcurrent. When the current exceeds overcurrent threshold, the comparator output (CMP_OUT) signal goes high. This signal from the comparator drives through the Q1 transistor to the gate of the high-side switch, causing the switch to shut down. The Q1 transistor helps isolate CMP_OUT from the high voltage of the Supply. There are three location options to have shunt resistor to measure unidirectional current. Option 1 and Option 2 are high-side current sensing, and Option 3 is low-side current sensing. Though both are high-side current sensing, Option 1 accounts for the current flowing through the Q1 transistor, and Option 2 does not. The advantages of high-side current sensing are that high-side sensing options do not contribute to ground disturbances and that high-side sensing can detect load shorts. In high-side current sensing, input common-mode is close to the power supply so a current-sensing amplifier with high CMRR and high common-mode is required for high-accuracy measurement. The low-side current sensing does not require a high-voltage, current-sensing amplifier as common mode remains very close to the ground. The disadvantages of low-side current sensing are that low-side sensing options contribute to ground disturbances and that low-side current sensing cannot detect load shorts.

Figure 7-5 High-Side Switch for Overcurrent Shutdown