MP4559 is a high frequency step-down switching regulator with integrated internal high side high voltage power MOSFET. It provides 1.5A output with current mode control for fast loop response and easy compensation. The wide 3.8V to 55V input range accommodates a variety of step-down applications, including those in automotive input environment. High power conversion efficiency over a wide load range is achieved by scaling down the switching frequency at light load condition to reduce the switching and gate driving losses. The frequency foldback helps prevent inductor current runaway during start-up and thermal shutdown provides reliable, fault tolerant operation. By switching at 2MHz, the MP4559 is able to prevent EMI (Electromagnetic Interference) noise problems, such as those found in AM radio and ADSL applications. Typical applications include high voltage power conversion, automotive systems, industrial power systems, distributed power systems and battery powered systems.