DESCRIPTION
The LTC®3563 is a high effi ciency monolithic synchronous buck converter using a constant frequency, current mode architecture. A voltage select input allows the user to program the output voltage to 1.28V or 1.87V. Supply current during operation is only 26µA, dropping to <1µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3563 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. Internal power switches are optimized to provide high effi ciency and eliminate the need for an external Schottky diode.

FEATURES
■ High Effi ciency: Up to 96%
■ Pin Selectable Output Voltage: 1.28V/1.87V
■ Low Ripple (<20mVP-P) Burst Mode® Operation:
   IQ = 26µA
■ Very Low Quiescent Current: Only 26µA
■ 2.5V to 5.5V Input Voltage Range
■ 2.25MHz Constant Frequency Operation
■ Low Dropout Operation: 100% Duty Cycle
■ No Schottky Diode Required
■ Internal Soft-Start Limits Inrush Current
■ Shutdown Mode Draws <1µA Supply Current
■ ±2% Output Voltage Accuracy
■ Current Mode Operation for Excellent Line and Load
   Transient Response
■ Overtemperature Protected
■ Available in 2mm × 2mm 6-Lead DFN

APPLICATIONS
■ Cellular Telephones
■ Wireless and DSL Modems
■ Digital Cameras
■ MP3 Players
■ PDAs and Other Handheld Devices