The MAX1765 is a high-efficiency, low-noise, step-up DC-DC converter intended for use in battery-powered wireless applications. This device operates at a high 1MHz fixed frequency while maintaining an exceptionally low quiescent supply current (200µA). Its small external components and tiny package make this device an excellent choice for small hand-held applications that require the longest possible battery life.The MAX1765 uses a synchronous-rectified pulse-width-modulation (PWM) boost topology to generate 2.5V to 5.5V outputs from a wide range of input sources, such as one to three alkaline or NiCd/NiMH cells or a single lithium-ion (Li+) cell. Maxim's proprietary architecture significantly improves efficiency at low load currents while automatically transitioning to fixed-frequency PWM operation at medium to high load currents to maintain excellent full-load efficiency. Forced-PWM mode is available for applications that require constant-frequency operation at all load currents, and the MAX1765 may also be synchronized to an external clock to protect sensitive frequency bands in communications equipment.The MAX1765's low-dropout (LDO) linear regulator and DC-DC converter have separate shutdown control. The linear regulator's 250mΩ pass device maintains excellent dropout voltage at currents up to 500mA. The MAX1765 also features analog soft-start and current-limit functions to permit optimization of efficiency, external component size, and output voltage ripple.The MAX1765 comes in a 16-pin QSOP package and a thermally enhanced 16-pin TSSOP-EP.ApplicationsHandheld Instruments (PDAs, Palmtops)Palmtop ComputersPCS PhonesPersonal CommunicatorsPortable Audio PlayersWireless Handsets