The SC416 is a versatile, constant on-time, pseudofixed-frequency, dual synchronous buck PWM controller intended for notebook computers and other battery operated portable devices. The SC416 contains all the features needed to provide cost-effective control of two independent switchmode power supplies. The SC416 provides adjustable voltage tracking during start-up and shut-down, making it an effective solution for a variety of applications where the voltage differential between supply rails must meet defined limits during all operating conditions including start-up and shutdown. The SC416 supports proportional tracking which gives equal start-up and shut-down times for both outputs, and can also provide coincident tracking where the two output voltages are equal during the lower voltage's start-up and shut-down ramp.