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LTC3440 - Micropower Synchronous Buck-Boost DC/DC Converter

The LTC3440 is a high efficiency, fixed frequency, Buck-Boost DC/DC converter that operates from input voltages above, below or equal to the output voltage. The topology incorporated in the IC provides a continuous transfer function through all operating modes, making the product ideal for single lithium-ion, multicell alkaline or NiMH applications where the output voltage is within the battery voltage range.

The device includes two 0.19Ohm N-channel MOSFET switches and two 0.22Ohm P-channel switches. Switching frequencies up to 2MHz are programmed with an external resistor and the oscillator can be synchronized to an external clock. Quiescent current is only 25µA in Burst Mode operation, maximizing battery life in portable applications. Burst Mode operation is user controlled and can be enabled by driving the MODE/SYNC pin high. If the MODE/SYNC pin has either a clock or is driven low, then fixed frequency switching is enabled.

Other features include a 1µA shutdown, soft-start control, thermal shutdown and current limit. The LTC3440 is available in the 10-pin thermally enhanced MSOP package.

Protected by U.S. Patents including 6404251, 6166527.

Features Single Inductor Fixed Frequency Operation with Battery Voltages Above, Below or Equal to the Output Synchronous Rectification: Up to 96% Efficiency 25µA Quiescent Current in Burst Mode® Operation Up to 600mA Continuous Output Current No Schottky Diodes Required (VOUT < 4.3V) VOUT Disconnected from VIN During Shutdown 2.5V to 5.5V Input and Output Range Programmable Oscillator Frequency from 300kHz to 2MHz Synchronizable Oscillator Burst Mode Enable Control <1µA Shutdown Current Small Thermally Enhanced 10-Pin MSOP and (3mm × 3mm) DFN Packages Typical Application

Applications Palmtop Computers Handheld Instruments MP3 Players Digital Cameras Packaging

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