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

The LTC3548-2 is a dual, 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 ≤1.2mm. For channel 1, the output voltage is fixed at 1.8V/800mA; for channel 2, the output voltage is adjustable from 0.6V to VIN. Internal synchronous 0.35Ω, 1.2A/0.7A 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 run time, 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.

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/800mA Fixed Output and 400mA Adjustable Output Voltage

* Only 40μA Quiescent Current (Both Channels)

* 2.25MHz Constant Frequency Operation

* High Switch Current Limits: 1.2A and 0.7A

* No Schottky Diodes Required

* Low RDS(ON) Internal Switches: 0.35Ω