DESCRIPTION

The LTC?3547B is a dual, 2.25MHz, constant-frequency, synchronous step-down DC/DC converter in a tiny 3mm × 2mm DFN package. 100 duty cycle provides low dropout operation, extending battery life in portable systems. Low output voltages are supported with the 0.6V feedback reference voltage. Each regulator can supply 300mA continuous output current.

FEATURES

■ High Effi ciency (Up to 96) Dual Step-Down

Outputs

■ 300mA Output Current per Channel at VIN = 3V

■ 2.25MHz Constant-Frequency Operation

■ 2.5V to 5.5V Input Voltage Range

■ Low Dropout Operation: 100 Duty Cycle

■ No Schottky Diodes Required

■ Internally Compensated for All Ceramic Capacitors

■ Independent Internal Soft-Start for Each Channel

■ Available in Fixed Output Versions

■ Current Mode Operation for Excellent Line and Load

Transient Response

■ 0.6V Reference Allows Low Output Voltages

■ Short-Circuit Protected

■ Ultralow Shutdown Current: IQ < 1μA

■ Low Profi le (0.75mm) 8-Lead 3mm × 2mm

DFN Package

APPLICATIONS

■ Cellular Telephones

■ Digital Still Cameras

■ Wireless and DSL Modems

■ Portable Media Players

■ PDAs/Palmtop PCs