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LTC3548-2 - Dual Synchronous, Fixed/Adjustable Output, 2.25MHz Step-Down DC/DC Regulator

The LTC®3548-2 is a dual, 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 ≤1.2mm. For channel 1, the output voltage is fixed at 1.8V/800mA; for channel 2, the output voltage is adjustable from 0.6V to VIN. Internal synchronous 0.35Ω, 1.2A/0.7A power switches provide high efficiency without the need for external Schottky diodes.

A user selectable mode input is provided to allow the user to trade-off noise ripple for low power efficiency. Burst Mode® operation provides high efficiency at light loads, while Pulse Skip Mode provides low noise ripple at light loads.

To further maximize battery run time, 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.

Features High Efficiency: Up to 95% 1.8V/800mA Fixed Output and 400mA Adjustable Output Voltage Only 40μA Quiescent Current (Both Channels) 2.25MHz Constant Frequency Operation High Switch Current Limits: 1.2A and 0.7A 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 Power-On Reset Output Externally Synchronizable Oscillator Small Thermally Enhanced 3mm × 3mm DFN Package Typical Application

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

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