The AT1621 provides complete control and protection for four voltages in high-performance, graphics intensive computer applications. It integrates a PWM controller and three linear controllers into a 28-pin SOIC package. One PWM controller regulates the CPU core voltage with a synchronous-rectified buck topology. The linear controllers regulate the computer system's AGP 1.5V or 3.3V bus power, the 1.5V GTL bus power, and the 1.8V power for the North/South Bridge core voltage and/or cache memory circuits.