5V-Output, Step-Up, Current-Mode PWM DC-DC Converter

The MAX751 is a +5V-output, CMOS, step-up, switch­-mode DC-DC converter. Minimum input start-up voltage is 1.2V. From a 2.7V supply, the output current capability is guaranteed to be 150mA. Battery-saving features include 86% typical full-load efficiency, 2mA operating quiescent supply current, and 35µA shutdown supply current. The shutdown mode can be directly controlled by a microprocessor via the logic-compatible SHON pin.

The MAX751 is tested in-circuit, so output power speci­fications are guaranteed over all line, load, and temper­ature ranges. The typical operating circuit uses tiny surface-mounted components, including a miniature 22µH inductor, and fits into less than 0.5in2.

The MAX751 uses current-mode pulse-width modulation (PWM) control to provide precise output regulation and low subharmonic noise. A fixed 170kHz oscillator fre­quency facilitates ripple filtering and allows for the use of tiny external capacitors.

For higher-current solutions, refer to the MAX731/MAX752 and MAX848/MAX849 data sheets and evaluation kit manuals. The MAX751 can be evaluated using the MAX731 evaluation kit {order MAX731EVKIT-DIP and a sample of the MAX751CPA).

APPLICATIONS

* Local +5V Supply in +3V-Only Systems Cellular Phones

* RF Transmitter Supply

* Palmtop and Notebook Computers

* Battery-Powered and Hand-Held Instruments

* +5V Preset Output

* Guaranteed 15GmA Output Current

* 1.2V Start-Up Supply Voltage

* 88% Typical Efficiencies at Full Load

* Small 22µH Inductor - No Component Design Required