DESCRIPTION
The LTC®3548-1 is a dual, fixed output, constant-frequency, synchronous step-down DC/DC converter. Intended for low power applications, it operates from 2.5V to 5.5V input voltage range and has a constant 2.25MHz switching frequency, allowing the use of tiny, low cost capacitors and inductors with a profile ≤1mm. The output voltage for channel 1 is fixed at 1.8V and for channel 2 is fi xed at 1.575V. Internal synchronous 0.35Ω, 1.2A/0.7A power switches provide high efficiency without the need for external Schottky diodes. Burst Mode® operation provides high effi ciency at light loads.

FEATURES
■ High Effi ciency: Up to 95%
■ 1.8V at 800mA/1.575V at 400mA
■ Very Low Quiescent Current: Only 40μA
■ 2.25MHz Constant-Frequency Operation
■ High Switch Current: 1.2A and 0.7A
■ No Schottky Diodes Required
■ VIN: 2.5V to 5.5V
■ Current Mode Operation for Excellent Line and Load Transient Response
■ Short-Circuit Protected
■ Low Dropout Operation: 100% Duty Cycle
■ Ultralow Shutdown Current: IQ < 1μA
■ Small Thermally Enhanced 3mm × 3mm DFN Packages

APPLICATIONS
■ PDAs/Palmtop PCs
■ Digital Cameras
■ Cellular Phones
■ Portable Media Players
■ PC Cards
■ Wireless and DSL Modems