The MC34166, MC33166 series are high performance fixed frequency power switching regulators that contain the primary functions required for dc−to−dc converters. This series was specifically designed to be incorporated in step−down and voltage−inverting configurations with a minimum number of external components and can also be used cost effectively in step−up applications. These devices consist of an internal temperature compensated reference, fixed frequency oscillator with on−chip timing components, latching pulse width modulator for single pulse metering, high gain error amplifier, and a high current output switch. Protective features consist of cycle−by−cycle current limiting, undervoltage lockout, and thermal shutdown. Also included is a low power standby mode that reduces power supply current to 36 A.