LTC1772

U U LTC1772 Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23 FEATURES ■ High Efficiency: Up to 94% ■ High Output Currents Easily Achieved ■ Wide VIN Range: 2.5V to 9.8V ■ Constant Frequency 550kHz Operation ■ Burst Mode® Operation at Light Load ■ Low Dropout: 100% Duty Cycle ■ Tiny 6-Lead SOT-23 Package ■ 0.8V Reference Allows Low Output Voltages ■ Current Mode Operation for Excellent Line and Load Transient Response ■ Low Quiescent Current: 270µA ■ Shutdown Mode Draws Only 8µA Supply Current ■ ±2.5% Reference Accuracy U APPLICATIO S ■ One or Two Lithium-Ion-Powered Applications ■ Cellular Telephones ■ Wireless Modems ■ Portable Computers ■ Distributed 3.3V, 2.5V or 1.8V Power Systems ■ Scanners DESCRIPTIO The LTC®1772 is a constant frequency current mode stepdown DC/DC controller providing excellent AC and DC load and line regulation. The device incorporates an accurate undervoltage lockout feature that shuts down the LTC1772 when the input voltage falls below 2.0V. The LTC1772 provides a ±2.5% output voltage accuracy and consumes only 270µA of quiescent current. For applications where efficiency is a prime consideration, the LTC1772 is configured for Burst Mode operation, which enhances efficiency at low output current. To further maximize the life of a battery source, the external P-channel MOSFET is turned on continuously in dropout (100%dutycycle).In shutdown, the device draws a mere 8µA. High constant operating frequency of 550kHz allows the use o...