The R5543K001D-E2 from Nisshinbo Micro Devices is a CMOS-based dual supply voltage load switch IC that is designed for supplying the power from the secondary power source such as the output of a step-down DC-DC converter to the load circuit. It requires an input voltage of 0.6 - 4.8 V and provides an output current of 3 A. This power switch features a built-in N-channel transistor to provide a low dropout voltage and prevent the reverse current during shutdown mode. It is equipped with various internal circuits, including an internal voltage step-up circuit, a soft-start circuit, a thermal shutdown circuit, a chip enable circuit and an under-voltage lockout (UVLO) circuit. This power switch features an auto-discharge function which is designed to improve the safety and efficiency of the device. It is available in a surface-mount package that measures 1.6 x 1.2 x 0.4 mm and is ideal for optical communication modules, smartphones, tablet PCs, storage, and portable device applications.