Space-Saving Step-Down Controller Integrates Four Voltage Regulators

The MAX17101 is a dual, Quick-PWM step-down controller with synchronous rectification for generating 5-V/3.3-V supplies in notebook computers, tablet PCs, and other battery-powered systems. Four output-voltage regulators are integrated in the tiny chip allowing it to save space while generating multiple supplies for notebook computers. An internal, 100-mA linear regulator can be used to generate either the 5-V bias needed for power-up or other lower-power, "always-on" suspend supplies. The controller also includes a low-current (5 mA), "always-enabled" linear regulator to power the real-time clock when all other notebook regulators are disabled. Low-side MOSFET sensing provides low-cost, efficient current sensing for valley current-limit protection. The 5-V/3.3-V 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 can 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 PWM controllers, while also avoiding the problems caused by widely varying switching frequencies in conventional constant-on-time and constant-off-time PWM schemes. The MAX17101 is available in a 5-mm x 5-mm 32-pin TQFN package, and is fully specified over the –40°C to +85°C extended industrial temperature range. Prices start at $4.00 in 1000-unit lots. MAXIM INTEGRATED PRODUCTS, Sunnyvale, CA. (800) 998-8800.