LTC3407-3 Datasheet

• Very Low Quiescent Current: Only 40µA
• 1.8V at 800mA/3.3V at 800mA
• High Efficiency: Up to 95%
• 2.25MHz Constant Frequency Operation
• High Switch Current: 1.2A on Each Channel
• No Schottky Diodes Required
• Low R_DS(ON) Internal Switches: 0.35Ω
• V_IN: 3.3V 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: I_Q < 1µA
• Power-On Reset Output
• Externally Synchronizable Oscillator
• Small Thermally Enhanced 3mm × 3mm DFN Package

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

The LTC3407-3 is a dual, constant frequency, synchronous step down DC/DC converter. Intended for low power applications, it operates from 3.3V 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 ≤1.0mm. Internal synchronous 0.35Ω, 1.2A 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 life, 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.