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SC451

Portable IMVP-IV™ and IMVP-IV+™

Single Phase Power Supply Controller

POWER MANAGEMENT

June 6, 2005

Description

Features

Applications

Conceptual Application Circuit

solution

setting

DeeperSleep mode changes

The SC451 PowerStep IV™ IC is a single chip high-perfor-

mance Hysteretic PWM controller. With its integrated

SmartDriver™, it powers advanced IMVP-IV™ and IMVP4+™

processors. The SC451 features extended Intel Mobile Volt-

age Positioning (IMVP™) to increase battery life by reduc-

ing the voltage at the processor when it is heavily loaded.

It directly supports Intel’s SpeedStep® processors for even

longer battery life. The SC451 fully supports the Intel®

Geyserville-III core voltage specification. It provides direct

“deeper sleep” mode and boot voltage support. Automatic

“power-save” is present to prevent negative current flow in

the low-side FET during light loading conditions, saving even

more power. The high side driver initially turns on with a

weak drive to reduce ringing, EMI, and capacitive turn-on

of the low side.

A 6-bit DAC, accurate to 0.85%, sets the output voltage

reference, and implements the 0.700V to 1.708V range

required by the processor. The hysteretic converter uses a

comparator without an error amplifier, and therefore pro-

vides the fastest possible transient response, while avoid-

ing the stability issues inherent to classical PWM control-

lers. The DAC is externally slew rate limited to minimize

transient currents and audible noise.

The SC451 operates from 5VDC and also features soft-

start, an open-drain PWRGD signal with power-good blank-

ing, and an enable input. Programmable current limiting

shuts down the SC451 after 32 current limit pulses. It

comes in both a TSSOP-28 and TSSOP-38 package. The

TSSOP-38 provides a pin-to-pin upgrade to a dual-phase

solution using Semtech’s dual-phase controller, SC450.

PowerStep IV™ is a trademark of Semtech

Corporation.

Other trademarks or registered trademarks may be

claimed as the property of others.

S C 45 1 S ingle P h a s e

IM V P -IV /IM V P -IV +

Pow e r Sup p ly

Sm a rt

Driv e r

PW M

Co n tro lle r

V ID Logic

an d D A C

VID (5 :0 )

VIN

V

5

V

CC A

VC O R E

0.700V -1 .708V