LTC3407-3

LTC3407-3 Dual Synchronous, 1.8V/0.8A and 3.3V/0.8A 2.25MHz Step-Down DC/DC Regulator FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 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 RDS(ON) Internal Switches: 0.35Ω VIN: 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: IQ < 1µA Power-On Reset Output Externally Synchronizable Oscillator Small Thermally Enhanced 3mm × 3mm DFN Package The LTC®3407-3 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