800mA, 2MHz, PWM DC-to-DC Step-Down Converter with Reset

The MAX1572 is a fixed-frequency, synchronous step-down DC-to-DC converter to power low-voltage microprocessor/DSP cores in portable equipment requiring high efficiency in a limited PC board area. The features are optimized for high efficiency over a wide load range, small external component size, low output ripple, and excellent transient response. The input supply voltage range is from 2.6V to 5.5V, while the output is internally fixed from 0.75V to 2.5V in 50mV increments with a guaranteed output current of 800mA. The high 2MHz switching allows tiny low-cost capacitors and a low-profile inductor, while the power-saving pulse-group mode reduces quiescent current to 48µA (typ) with light loads. To reduce noise and RF interference, the converter can be configured to provide forced-PWM operation.

The MAX1572 includes a low on-resistance internal MOSFET switch and synchronous rectifier to maximize efficiency and minimize external component count. No external diode is needed. Other features include soft-start to eliminate inrush current at startup and a 170ms (min) RESET-bar output to provide power-on/undervoltage reset. The MAX1572 is available in a 12-pin, 4mm x 4mm thin QFN package with exposed paddle.

Applications

* Cell Phones/Smartphones * Digital Cameras and Camcorders * Handheld Instruments (PDAs, Palmtops) * MP3 and DVD Players * PCMCIA Cards * PDAs, Palmtops, and Notebook Computers

* Up to 97% Efficiency

* 2MHz PWM Switching

* 800mA Guaranteed Output Current

* Low 48µA Quiescent Current

* Power-Saving Modes: Pulse-Group, Pulse-Skip, Forced-PWM Mode

* 0.75V to 2.5V Preset Output Range (in 50mV Increments)

* Voltage-Positioning Load Transients

* 5mVP-P Output Ripple

* Tiny 2.2µH Inductor

* 10µF Ceramic Output Capacitor

* Low 0.1µA Shutdown Current

* No External Schottky Diode Required

* Soft-Start with Zero Inrush Current

* 170ms (min) active-low RESET Output

* Small 12-Pin, 4mm x 4mm Thin QFN Package