POWER MANAGEMENT

1

SC198A

Dual DC-DC Buck Converter

with High Current Capability

Features

Input voltage range — 2.7V to 5.5V

Dual buck converters with independent control

High efficiency — over 90% peak

Up to 800mA Load

Programmable output voltages per channel — 8

Fixed-frequency operation — 1MHz

Optional SYNC clock input

Optional power-save under light-load conditions

Shutdown current <1μA

Soft-start to limit in-rush current

4mm x 4mm MLPQ package

Applications

Mobile phones

Cordless phones

MP3 players

Digital cameras

PDAs

Single Li-Ion cell or (3) NiMH/NiCd cell devices

Digital multimedia broadcast (DMB) devices

Portable gaming systems

Description

The SC198A is a dual high-efficiency synchronous buck

converter designed for use in low power applications.

Each converter is capable of supplying up to 800mA of

average current at one of eight programmable output

voltages used as microprocessor supply voltages.

The SC198A uses a single control logic block for the two

converters, but their controls can be set independently.

The device uses a flexible clocking method allowing the

user to set the fixed internal 1MHz oscillator or synchro-

nize the clock to an external source. The device also has an

optional power-save mode that optimizes efficiency for

light loads.

The SC198A provides output voltage flexibility while con-

serving board space by using control pins to select the

output voltage. This eliminates at least four parts from the

traditional dual buck converter bill of materials.

Typical Application Circuit

September 26, 2007

4.7μH

4.7μH

VINA

VINR

VINB

ENA

CTLA0

CTLA1

CTLA2

ENB

CTLB0

CTLB1

CTLB2

LXA

VOUTA

GNDA

LXB

VOUTB

GNDB

MODE/SYNC

GNDR

SC198A

VOUTA

VOUTB

VBATT