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LTC1773 - Synchronous Step-Down DC/DC Controller

The LTC®1773 is a current mode synchronous buck regulator controller that drives external complementary 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 550kHz, allowing the use of small surface mount inductors. For switching-noise sensitive applications, it can be synchronized up to 750kHz. 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.

Synchronous rectification increases efficiency and eliminates the need for a Schottky diode, saving components and board space. The LTC1773 comes in a 10-lead MSOP package.

特点 High Efficiency: Up to 95% Constant Frequency 550kHz Operation VIN from 2.65V to 8.5V VOUT from 0.8V to VIN OPTI-LOOP™ Compensation Minimizes COUT Synchronizable up to 750kHz 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 Quiescent Current: 80µA Low Shutdown IQ = 10µA ±1.5% Reference Accuracy Precision 2.5V Undervoltage Lockout Available in 10-Lead MSOP 典型应用

应用 Cellular Telephones RF PA Supply Portable Instruments Wireless MODEMS Distributed Power Systems Notebook and Palm Top Computers, PDAs Single and Dual Cell Lithium-Ion Powered Devices 封装信息

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