DESCRIPTION
The LTC®3548A is a dual, constant frequency, synchronous step-down DC/DC converter. Intended for low power applications, it operates from a 2.5V to 5.5V input voltage range and has a constant 2.25MHz switching frequency, enabling the use of tiny, low cost capacitors and inductors 1mm or less in height. Each output voltage is adjustable from 0.6V to 5V. Internal synchronous 0.35Ω, 0.7A/1.2A power switches provide high efficiency without the need for external Schottky diodes.

FEATURES
■ High Effi ciency: Up to 95%
■ Low Ripple (<35mVP-P) Burst Mode Operation;
   IQ = 40μA
■ 2.25MHz Constant Frequency Operation
■ High Switch Current: 0.7A and 1.2A
■ No Schottky Diodes Required
■ Low RDS(ON) Internal Switches: 0.35Ω
■ Current Mode Operation for Excellent Line
   and Load Transient Response
■ Short-Circuit Protected
■ Low Dropout Operation: 100% Duty Cycle
■ Ultralow Shutdown Current: IQ <1μA
■ Output Voltages from 5V down to 0.6V
■ Power-On Reset Output
■ Externally Synchronizable Oscillator
■ Optional External Soft-Start
■ Small Thermally Enhanced MSOP and 3mm × 3mm
   DFN Packages

APPLICATIONS
■ PDAs/Palmtop PCs
■ Digital Cameras
■ Cellular Phones
■ Wireless and DSL Modems