PROGRAMMABLE SYNCHRONOUS DC/DC

CONVERTER WITH LOW DROPOUT

REGULATOR CONTROLLER

SC1172/3

© 1999 SEMTECH CORP.

October 25, 1999

652 MITCHELL ROAD NEWBURY PARK CA 91320

1

ORDERING INFORMATION

DESCRIPTION

The SC1172/3 combines a synchronous voltage mode

controller with a low-dropout linear regulator providing

most of the circuitry necessary to implement two DC/DC

converters for powering advanced microprocessors such

as Pentium

The SC1172/3 switching section features an integrated 5

bit D/A converter, pulse by pulse current limiting,

integrated power good signaling, and logic compatible

shutdown. The SC1172/3 switching section operates at

a fixed frequency of 200kHz, providing an optimum

compromise between size, efficiency and cost in the

intended application areas. The integrated D/A con-

verter provides programmability of output voltage from

2.0V to 3.5V in 100mV increments and 1.30V to 2.05V

in 50mV increments with no external components.

The SC1172/3 linear section is a high performance

positive voltage regulator design for either the GTL bus

supply at 1.5V (SC1172) or an adjustable output

(SC1173).

The output of the linear regulator can provide up to 5A or

more with the appropriate external MOSFET.

Pentium is a registered trademark of Intel Corporation

PIN CONFIGURATION

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

BLOCK DIAGRAM

FEATURES

ments

APPLICATIONS

Part Number

(1)

Package

Linear

Voltage

Temp.

Range (T

SC1172CSW

SO-24

1.5V

0° to 125°C

SC1173CSW

SO-24

Adj.

0° to 125°C

Note:

(1) Add suffix ‘TR’ for tape and reel.

Top View

(24 Pin SOIC)

NC

AGND

OVP

NC

VCC

LDOS

CS-

PWRGOOD

PGNDL

CS+

DH

PGNDH

LDOV

GATE

VID3

VID0

VID2

VID1

VOSENSE

DL

EN

BSTL

BSTH

VID4

2

1

6

3

5

4

8

7

12

9

11

10

23

24

19

22

20

21

17

13

16

14

15

18

LDOV

GATE

LDOS

PGNDL

DL

BSTL

PGNDH

DH

BSTH

EN

VCC

CS+

CS-

VID3

VID4

VID2

VID0

VID1

VOSENSE

PWRGOOD

OVP

VCC

70mV

CURRENT LIMIT

1.25 REF

D/A &

LEVEL SHIFT

AND HIGH SIDE

MOSFET DRIVE

SHUT-

DOWN

LOGIC

OSCILLATOR

R

S

Q

SHOOT-

THRU

CONTROL

SYNCHRONOUS

MOSFET DRIVER

ERROR

AMP

AGND

FET

CONTROLLER

1.25V

REF

OPEN

COLLECTORS

VCC