LTC3772B

U U LTC3772B Micropower No RSENSE Constant Frequency Step-Down DC/DC Controller FEATURES ■ No Current Sense Resistor Required ■ 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 Pulse Skipping 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 U APPLICATIO S ■ 1- or 2-Cell Li-Ion Battery-Powered Applications ■ Wireless Devices ■ Portable Computers ■ Distributed Power Systems DESCRIPTIO The LTC®3772B is a constant frequency current mode step-down DC/DC controller in a low profile 8-lead SOT-23 (ThinSOTTM) and a 3mm × 2mm DFN package. The No RSENSETM architecture eliminates the need for a current sense resistor, improving efficiency and saving board space. The LTC3772B automatically switches into pulse skipping operation at light loads. It consumes only 200µA of quiescent current under a no-load condition. The LTC3772B 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 inducto...