LTC1773 Datasheet | Linear Technology

LTC1773 Synchronous Step-Down DC/DC Controller Features - - - - - - - - - - - - - - - - DESCRIPTIO High Efficiency: Up to 95% Constant Frequency 550k Hz Operation VIN from 2.65V to 8.5V VOUT from 0.8V to VIN OPTI-LOOP® pensation Minimizes COUT Synchronizable up to 750k Hz Selectable Burst Mode Operation Low Quiescent Current: 80µA Low Dropout Operation: 100% Duty Cycle Secondary Winding Regulation Soft-Start Current Mode Operation for Excellent Line and Load Transient Response Low Shutdown IQ = 10µA ±1.5% Reference Accuracy Precision 2.5V Undervoltage Lockout Available in 10-Lead MSOP The LTC®1773 is a current mode synchronous buck regulator controller that drives external plementary power MOSFETs using a fixed frequency architecture. The operating supply range is from 2.65V to 8.5V, making it suitable for 1- or 2-cell lithium-ion battery powered applications. Burst Mode® operation provides high efficiency at low load currents. 100% duty cycle provides low dropout operation which extends operating time in battery-operated systems. The operating frequency is internally set at 550k Hz, allowing the use of small surface mount inductors. For switching-noise sensitive applications, it can be synchronized up to 750k Hz. Peak current limit is user programmable with an external high side sense resistor. A SYNC/FCB control pin guarantees regulation of secondary windings regardless of load on the main output by forcing continuous operation. Burst Mode operation is inhibited during synchronization or when the SYNC/FCB pin is pulled low to reduce noise and RF interference. Soft-start is provided by an external capacitor. U APPLICATIO S - - - - - - - Cellular Telephones RF PA Supplies Portable Instruments Wireless MODEMS Distributed Power Systems Notebook and Palm Top puters, PDAs Single and Dual Cell Lithium-Ion Powered Devices TYPICAL APPLICATIO SYNC/FCB w RSENSE 0.025Ω L1 3µH CIN 68µF EFFICIENCY (%) RUN/SS SENSE- 0.1µF 47p F 220p F 30k VFB ITH LTC1773 SW...