VRM9.0 PROGRAMMABLE, MULTI-PHASE,

HIGH PERFORMANCE PWM CONTROLLER

SC1146

© 2000 SEMTECH CORP.

652 MITCHELL ROAD NEWBURY PARK CA 91320

July 25, 2000

1

The SC1146 is patent pending

Pentium is a registered trademark of Intel Corporation

BLOCK DIAGRAM

FEATURES

put ripple voltage

output voltage Microprocessors

+12V supply

APPLICATIONS

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

DEVICE

(1)

PACKAGE

TEMP. (T

SC1146CSW.TR

SO-24

0 - 85°C

ORDERING INFORMATION

Note:

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

contains 1000 devices.

DESCRIPTION

The SC1146 is the latest, high performance, multi-

phase (PWM) controller designed for high power mi-

croprocessors requiring ultra fast transient response.

The SC1146 is programmable for the voltage range

required by the latest Microprocessors . Utilizing a

novel and unique design, the controller distributes the

output load across (up to) four converter channels by

digitally phase shifting the PWM outputs. This ap-

proach greatly reduces the stress and heat on the out-

put stage components while lowering input ripple cur-

rent by as much as 80%. Accurate current sharing

among the four phases is achieved by precision design

techniques and trimming of critical elements.

The high speed transconductance error amplifier is ex-

ternally initialized using a soft-start capacitor allowing

the controller to “wake-up” without overshoot, thus pro-

tecting the low voltage microprocessor loads. The out-

put drive voltage to the power MOSFETs is pro-

grammable to minimize switching losses in the drive

circuitry.

The output voltage is digitally programmable by means

of a 5 bit DAC (new codes). A single resistor programs

the master clock frequency (8MHz max) or the clock

can be supplied by an external source where exact fre-

quency control is desired. The number of operating

phases is programmed independently of the external

clock. The parts features under-voltage lock-out with

hysteresis and over-current protection.

PIN CONFIGURATION

Top View

(24-Pin SOIC)