The FAN5234 PWM controller provides high efficiency and regulation with an adjustable output from 0.9V to 5.5V that are required to power I/O, chip-sets, memory banks or peripherals in high-performance notebook computers, PDAs and Internet appliances. Synchronous rectification and hysteretic operation at light loads contribute to a high efficiency over a wide range of loads. The hysteretic mode of operation can be disabled if PWM mode is desired for all load levels. Efficiency is even further enhanced by using MOSFET's RDS(ON) as a current sense component.