The LM22677 series of regulators are monolithic integrated circuits which provide all of the active functions for a stepdown (buck) switching regulator capable of driving up to 5A loads with excellent line and load regulation characteristics. High efficiency (>90%) is obtained through the use of a low ON-resistance N-channel MOSFET. The series consists of a fixed 5V output and an adjustable version. The SIMPLE SWITCHER concept provides for an easy to use complete design using a minimum number of external components and National's WEBENCH design tool. National's WEBENCH tool includes features such as external component calculation, electrical simulation, thermal simulation, and Build-It boards for easy design-in. The switching clock frequency is provided by an internal fixed frequency oscillator which operates at 500 kHz. The switching frequency can also be adjusted with an external resistor or synchronized to an external clock up to 1MHz. It is also possible to selfsynchronize multiple regulators to share the same switching frequency. The LM22677 series also has built in thermal shutdown, current limiting and an enable control input that can power down the regulator to a low 25 A quiescent current standby condition.