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LTC1779 - 250mA Current Mode Step-Down DC/DC Converter in SOT-23

The LTC1779 is a constant frequency current mode step-down DC/DC converter in a 6-lead ThinSOT package. The part operates with a 2.5V to 9.8V input and can provide up to 250mA of output current. Current mode control provides excellent AC and DC load and line regulation. The device incorporates an accurate undervoltage lockout feature that shuts down the LTC1779 when the input voltage falls below 2V.

The LTC1779 boasts a ±2.5% output voltage accuracy and consumes only 135µA of quiescent current. For applications where efficiency is a prime consideration, the LTC1779 is configured for Burst Mode operation, which enhances efficiency at low output current.

To further maximize the life of a battery source, the internal P-channel MOSFET is turned on continuously in dropout (100% duty cycle). In shutdown, the device draws a mere 8µA. High constant operating frequency of 550kHz allows the use of a small external inductor.

The LTC1779 is available in a low profile (1mm) ThinSOT package.

Features High Efficiency: Up to 94% 250mA Output Current Wide VIN Range: 2.5V to 9.8V 550kHz Constant Frequency Operation Burst Mode™ Operation at Light Load Low Dropout: 100% Duty Cycle 0.8V Reference Allows Low Output Voltages ±2.5% Reference Accuracy Current Mode Operation for Excellent Line and Load Transient Response Low Quiescent Current: 135µA Shutdown Mode Draws Only 8µA Supply Current Low Profile (1mm) ThinSOT™ Package Typical Application

Applications 1- or 2-Cell Lithium-Ion-Powered Applications Cellular Telephones Wireless Modems Portable Computers Distributed 3.3V, 2.5V or 1.8V Power Systems Scanners Packaging

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