1

www.semtech.com

SC1476

Portable IMVP-IV Dual Phase

Power Supply Controller

POWER MANAGEMENT

Revision 7, December 2002

Description

Features

Applications

Typical Application Circuit

IMVP-IV compliant single chip solution

High speed hysteretic controller

6 bit VID programmable output

Integrated drivers with soft high side turn-on

Programmable softstart

Programmable boot voltage

Programmable DeeperSleep voltage

Dynamic phase current matching

Under-voltage lockout on VccA

Over-voltage protection on CORE

Current Limit protection on CORE

Thermal protection

Powergood flag with blanking during VID or

DeeperSleep mode changes

Automatic powersave at light load

Slew rate limited DAC

TSSOP-38 package

The SC1476 PowerStep™ IV IC is a single chip high-per-

formance hysteretic PWM controller. With its integrated

SmartDriver™, it powers advanced IMVP-IV processors.

sitioning (IMVP) to increase battery life by reducing the

voltage at the processor when it is heavily loaded. It

longer battery life. The SC1476 fully supports Intel’s

Geyserville-III core voltage specification. It provides di-

rect “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 con-

ditions, saving even more power. The high side driver ini-

tially 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 thereby provid-

ing 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 SC1476 operates from 3Vdc and 5Vdc and also fea-

tures soft-start, an open-drain PWRGD signal with power-

good blanking, and an enable input. Programmable cur-

rent limiting shuts down the SC1476 after 32 current

limit pulses. In addition, it comes in a space-saving

TSSOP-38 package.

SC1474

Dual Phase

Extended IMVP

CONTROLLER

VID [4:0]

Lo

+VCORE

+V_IN

+V_5

0.600V-1.75V

Up to 40A

Extended

IMVP

Logic

PWM

Controller

Power

Control

Signals

Smart

Driver

VID

Multiplexer

Lo

Co

Smart

Driver

Rcs

Rcs

+V_3

+V_VID

VID

Regulator

Controller

SC1474

Dual Phase

Extended IMVP

CONTROLLER

VID [4:0]

Lo

+VCORE

+V_IN

+V_5

0.600V-1.75V

Up to 40A

Extended

IMVP

Logic

PWM

Controller

Power

Control

Signals

Smart

Driver

VID

Multiplexer

Lo

Co

Smart

Driver

Rcs

Rcs

+V_3

+V_VID

VID

Regulator

Controller

VID[5:0]

VID[5:0]

VID[5:0]

VID[5:0]

VID[5:0]

Notebook and Laptop computers

Requests for a complete datasheet and

additional product information should be

directed to sales@semtech.com