The MP4558 is a high-frequency, step-down switching regulator with an integrated internal high-side high-voltage power MOSFET. It provides up to a 1A 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 automotive input. A 12? shutdown-mode supply current makes it suitable for battery-powered applications. A scaled-down switching frequency in light-load conditions provides high power-conversion efficiency over a wide load range while reducing switching and gate driver losses. The frequency fold-back prevents inductor current runaway during startup and thermal shutdown provides reliable, fault-tolerant operation. By switching at 2MHz, the MP4558 can prevent EMI (electromagnetic interference) noise problems, such as those found in AM radio and ADSL applications. The MP4558 is available in an SOIC8E and a 10-pin 3mm x 3mm QFN package.