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LTC3772 - Micropower No RSENSE Constant Frequency Step-Down DC/DC Controller

The LTC3772 is a constant frequency current mode step-down DC/DC controller in a low profile 8-lead SOT-23 (ThinSOT) and a 3mm × 2mm DFN package. The No RSENSE architecture eliminates the need for a current sense resistor, improving efficiency and saving board space.

The LTC3772 automatically switches into Burst Mode operation at light loads to increase efficiency at low output current. It consumes only 40µA of quiescent current under a no-load condition.

The LTC3772 incorporates an undervoltage lockout feature that shuts down the device when the input voltage falls below 2V. To maximize the runtime from a battery source, the external P-channel MOSFET is turned on continuously in dropout (100% duty cycle). High switching frequency of 550kHz allows the use of a small inductor and capacitors. An internal soft-start smoothly ramps the output voltage from zero to its regulation point.

Features No Current Sense Resistor Required 40µA No-Load Quiescent Current High Output Currents Easily Achieved Internal Soft-Start Ramps VOUT Wide VIN Range: 2.75V to 9.8V Low Dropout: 100% Duty Cycle Constant Frequency 550kHz Operation Low Ripple Burst Mode® Operation at Light Load Output Voltage as Low as 0.8V ±1.5% Voltage Reference Accuracy Current Mode Operation for Excellent Line and Load Transient Response Only 8µA Supply Current in Shutdown Low Profile 8-Lead SOT-23 (1mm) and (3mm × 2mm) DFN (0.75mm) Packages Typical Application

Applications 1- or 2-Cell Li-Ion Battery-Powered Applications Wireless Devices Portable Computers Distributed Power Systems Packaging

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