Step-down controller handles fast load steps

From Maxim Integrated Products comes the MAX17031 dual, Quick-PWM step-down controller with synchronous rectification specifically intended for generating 5V/3.3V supplies in battery-powered systems.

The device integrates a 100mA linear regulator that generates the 5V bias needed for power-up or other lower power, "always-on" suspend supplies. The controller also includes a low-current (5mA), "always-enabled" linear regulator to power the real-time clock when all other notebook regulators are disabled. The MAX17031 provides a complete, space-saving solution for notebook computers, tablet PCs and other portable devices.

The device employs low-side MOSFET sensing to provide a low-cost, highly-efficient current sense for valley current-limit protection. Combined with output overvoltage- and undervoltage-protection features, this current limit ensures robust output supplies. These 5V/3.3V SMPS outputs can save power by operating in pulse-skipping mode, or in ultrasonic mode to avoid audible noise.

Maxim's proprietary, Quick-PWM architecture enables the MAX17031 to handle fast load steps while maintaining a relatively constant operating frequency and inductor operating point over a wide range of input voltages. This approach circumvents the poor load-transient timing problems of fixed-frequency, current-mode PWMs, while also avoiding the problems caused by widely varying switching frequencies in conventional constant-on-time and constant-off-time PWM schemes.