PROGRAMMABLE SYNCHRONOUS DC/DC

CONVERTER, DUAL LOW DROPOUT

REGULATOR CONTROLLER

© 1999 SEMTECH CORP.

PRELIMINARY - January 6, 1999

652 MITCHELL ROAD NEWBURY PARK CA 91320

SC1185

SC1185A

1

DESCRIPTION

The SC1185 combines a synchronous voltage mode

controller with two low-dropout linear regulators

providing most of the circuitry necessary to

implement three DC/DC converters for powering

advanced microprocessors such as Pentium

The SC1185 switching section features an integrated

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

integrated power good signaling, and logic compatible

shutdown. The SC1185 switching section operates at

a fixed frequency of 140kHz, 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 compo-

nents.

The SC1185 linear sections are low dropout regula-

tors supplying 1.5V for GTL bus and 2.5V for non-

GTL I/O. The Reference voltage is made available for

external linear regulators.

Pentium is a registered trademark of Intel Corporation

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

BLOCK DIAGRAM

2.5V/ADJ.

1.5V/ADJ.

1.265V

FET

CONTROLLER

REF.

FET

CONTROLLER

REF.

VCC

CS-

CS+

EN

BSTH

DH

PGNDH

BSTL

DL

PGNDL

LDOV

GATE2

LDOS2

AGND

REF

VID4

VID3

VID2

VID1

VID0

VOSENSE

PWRGOOD

LDOS1

GATE1

D/A

PIN CONFIGURATION

AGND

GATE1

LDOS1

LDOS2

VCC

REF

PWRGOOD

CS-

CS+

PGNDH

DH

PGNDL

1

2

3

LDOV

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

VOSENSE

EN

BSTH

BSTL

DL

VID0

VID1

VID2

VID3

VID4

GATE2

Top View

(24 Pin SOIC)

FEATURES

APPLICATIONS

ORDERING INFORMATION

Part Number

(1)

Package

Linear

Voltage

Temp.

Range (T

SC1185CSW

SO-24

1.5V/2.5V 0° to 125°C

SC1185ACSW

(2)

SO-24

1.5V/2.5V 0° to 125°C

Note:

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

(2) SC1185A provides improved output tolerance. See

Output Voltage Table.