Maxim has a dual PWM step-down controller with synchronous rectification specifically intended for generating 5V/3.3V supplies in battery-powered systems.

The proprietary, Quick-PWM architecture is designed to enable 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,” said the supplier.

This 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 5mA, "always-enabled" linear regulator to power the real-time clock when all other notebook regulators are disabled.

More information: www.maxim-ic.com