LTC3407-3

Dual Synchronous, 1.8V/0.8A and 3.3V/0.8A 2.25MHz Step-Down DC/DC Regulator

* 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 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.

Iout

Fsw

Features

LTC3407

2x 600mA

1.5MHz

LTC3407-2

2x 800mA

2.25MHz

LTC3407-3

2x 800mA

2.25MHz

Fixed 1.8V/3.3V

LTC3407-4

2x 800mA

2.25MHz

Reduced POR Delay

LTC3407A

2x 600mA

1.5MHz

Low Ripple Burst Mode

LTC3407A-2

2x 800mA

2.25MHz

Low Ripple Burst Mode

Applications

* PDAs/Palmtop PCs

* Digital Cameras

* Cellular Phones

* Portable Media Players

* PC Cards

* Wireless and DSL Modems