The IR 3312(S) is a Fully Protected 4 terminal high side switch. The input signal is referenced to Vcc. When the input voltage Vcc - Vin is higher than the specified Vih threshold, the output power MOSFET is turned-on. When Vcc - Vin is lower than the specified Vil threshold, the output MOSFET is turned-off. A sense current proportional to the current in the power Mosfet is sourced to the Ifb pin. Over-current shutdown occurs when Vifb - Vin > 4.5 V. The current shutdown threshold is adjusted by selecting the proper RIfb. Either over-current and over-temperature latches off the switch. The device is reset by pulling the input pin high. Other integrated protections ( ESD, reverse battery, active clamp ) make the IR3312(S) very rugged and suitable for the automotive environment.