L4973 is a 3.5A step-down monolithic power switching regulator that delivers 3.3V or 5.1V at fixed voltages and uses a simple external divider to output adjustable voltage up to 50V. The device uses an internal power D-MOS transistor (with a typical RDS(on) of 0.15Ω) to obtain very high efficiency and very fast switching times. Switching frequency up to 300 kHz are achievable (the maximum power dissipation of the packages must be observed). A wide input voltage range between 8 V to 55 V and output voltages regulated from 3.3 V to 40 V cover the majority of the today applications. Features of this new generation of DC-DC converter includes pulse by pulse current limit, hiccup mode for output short circuit protect.