SC1409

© 2000 SEMTECH CORP.

652 MITCHELL ROAD NEWBURY PARK CA 91320

1 A Synchronous Switching Regulator

June 28, 2000

1

DESCRIPTION

The SC1409 is a versatile, voltage-mode switching

regulator designed for use in battery operated power

supply applications. A simple, fixed-voltage buck regu-

lator can be implemented using the SC1409 with a

minimum of external components. Internal MOSFETs

and control circuitry minimize board space and design

time.

The small device footprint allows for compact

circuit design.

SC1409 features include a temperature compensated

voltage reference, triangle wave oscillator,

hiccup

mode current limit, an internally compensated error

amplifier, overcurrent temperature protection,

soft

start, and under voltage lock out.

The SC1409 operates at a selectable, fixed frequency

of 300kHz or 500kHz, or can be synchronized to an

external clock within this range, providing an optimum

compromise between efficiency, external component

size, and cost.

FEATURES

APPLICATIONS

TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com

ORDERING INFORMATION

DEVICE

(1)

PACKAGE

SC1409ISTR

SO-8

Note:

(1) Only available in tape and reel packaging. A reel

contains 2500 devices.

+

C1

47uF/16V

L1

100uH

+

C2

47uF/16V

C3

0.033uF

Vout

U1

SC1409IS

8

1

2

3

4

5

6

7

ISET

SYNC/FSET

EN/SS

AGND

FB

PGND

PHASE

VIN

R4

C6

0.1uF

Vout

R3

R4

3.45V 1.87k 1.00k

3.30V 1.74k 1.00k

3.10V 1.58k 1.00k

2.90V 1.40k 1.00k

2.80V 1.33k 1.00k

2.50V 1.07k 1.00k

1.50V

249 1.00k

Vin=5V

R1

OPEN

R2

APPLICATION CIRCUIT