Low Input/Output Voltage Step-Up DC-DC Converter with Active-Low RESET

The MAX1947 is a compact, high-efficiency, step-up DC-DC converter that regulates output voltages from 1.8V to 3.3V to power µP/DSP cores, memory, and I/O rails in 1-and 2-cell alkaline/NiMH/NiCd battery-powered systems. It features an internal 800mA switch and synchronous rectifier to achieve up to 94% efficiency and to eliminate the need for an external Schottky diode.

High-frequency switching (up to 2MHz) results in low ripple and small external components, while automatic pulse skipping at light loads reduces supply current to just 70µA for extended battery life. Maxim's proprietary True Shutdown™ reduces supply current to just 2µA and fully discharges the output to ground. The converter is offered in fixed-output voltages of 1.8V, 2.5V, 3.0V, and 3.3V, requiring no feedback or compensation network. A 75ms active-low RESET output flag provides for power-on reset (POR) and undervoltage detection. The MAX1947 is available in a space-saving 8-pin TDFN package.

Applications

* Cordless Phones * Digital Still Cameras * MP3 Players, Pagers, and CD Players * Other Battery-Powered Systems * PDAs and Organizers * Portable Medical Equipment * Wireless Mice/Keyboards

* Low Input (0.7V) and Output (1.8V) Voltage Capability

* Internal Synchronous Rectifier

* High 94% Efficiency

* Fixed Output Voltages: 1.8V, 2.5V, 3V, and 3.3V

* Up to 2MHz Switching Allows Small External Components and Low Output Ripple

* Automatic Pulse Skipping at Light Loads for Extended Battery Life

* Low 70µA (typ) Operating Supply Current (Measured at OUT)

* Low 2µA Logic-Controlled Shutdown

* True Shutdown Fully Discharges Output to Ground

* Uses Only Small Ceramic Capacitors

* 75ms Active-Low RESET Output Flag