The MAX17020 is a dual Quick-PWMTM step-down power-supply (SMPS) controller with synchronous rectification, intended for main 5V/3.3V or I/O 1.5V/1.05V power generation in battery-powered systems. Lowside MOSFET sensing provides a simple low-cost, highly efficient current sense for valley current-limit protection. Combined with the output overvoltage and undervoltage protection features, this current limit ensures robust output supplies. The 5V/3.3V or 1.5V/1.05V SMPS outputs can save power by operating in pulse-skipping mode or in ultrasonic mode to avoid audible noise. Ultrasonic mode forces the controller to maintain switching frequencies greater than 20kHz at light loads. An internal 100mA linear regulator can be used to either generate the 5V bias needed for power-up or other lower power "always-on" suspend supplies. An independent bypass input allows automatic bypassing of the linear regulator when the SMPS is active.