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LTC3548-1 - Dual Synchronous, Fixed Output 2.25MHz Step-Down DC/DC Regulator

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 fixed 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 efficiency at light loads.

To further maximize battery runtime, the P-channel MOSFETs are turned on continuously in dropout (100% duty cycle), and both channels draw a total quiescent current of only 40µA. In shutdown, the device draws <1µA.

The LTC3548-1 is available in both thin (0.75mm) and ultra-thin (0.55mm) 3mm x 3mm DFN packages.

Features High Efficiency: 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 Typical Application

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

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