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

The LTC3548-1 is a dual, fixed output, 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 ≤1mm. The output voltage for channel 1 is fixed at 1.8V and for channel 2 is fixed at 1.575V. Internal synchronous 0.35Ω, 1.2A/0.7A power switches provide high efficiency without the need for external Schottky diodes. Burst Mode® operation provides high efficiency at light loads.

To further maximize battery runtime, 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.

The LTC3548-1 is available in both thin (0.75mm) and ultra-thin (0.55mm) 3mm × 3mm DFN packages.

Features

LTC3548A

Improved Burst Mode, Improved ESD, 2 Adjustable Outputs

LTC3548-2

One Fixed 1.8V Output, 1 Adjustable

LTC3548-1

Fixed 1.8V and 1.575V Outputs

LTC3548

2 Adjustable Outputs

Applications

* PDAs/Palmtop PCs

* Digital Cameras

* Cellular Phones

* Portable Media Players

* PC Cards

* Wireless and DSL Modems

* High Efficiency: Up to 95%

* 1.8V at 800mA/1.575V at 400mA

* Very Low Quiescent Current: Only 40µA

* 2.25MHz Constant-Frequency Operation

* High Switch Current: 1.2A and 0.7A

* No Schottky Diodes Required

* VIN: 2.5V to 5.5V