REV. A

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a

ADM1023*

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 2000

FUNCTIONAL BLOCK DIAGRAM

ACPI-Compliant

High-Accuracy Microprocessor

System Temperature Monitor

FEATURES

Next Generation Upgrade to ADM1021

On-Chip and Remote Temperature Sensing

Offset Registers for System Calibration

1 C Accuracy and Resolution on Local Channel

0.125 C Resolution/1 C Accuracy on Remote Channel

Programmable Over/Under Temperature Limits

Programmable Conversion Rate

Supports System Management Bus (SMBus) Alert

2-Wire SMBus Serial Interface

200

A Max Operating Current (0.25 Conversions/

Seconds)

1

A Standby Current

3 V to 5.5 V Supply

Small 16-Lead QSOP Package

APPLICATIONS

Desktop Computers

Notebook Computers

Smart Batteries

Industrial Controllers

Telecomms Equipment

Instrumentation

PRODUCT DESCRIPTION

The ADM1023 is a two-channel digital thermometer and under/

over temperature alarm, intended for use in personal computers

and other systems requiring thermal monitoring and management.

Optimized for the Pentium

allows systems designers to safely reduce temperature guard

banding and increase system performance. The device can

measure the temperature of a microprocessor using a diode-con-

nected PNP transistor, which may be provided on-chip in the

case of the Pentium III or similar processors, or can be a low

cost discrete NPN/PNP device such as the 2N3904/2N3906.

A novel measurement technique cancels out the absolute value

of the transistor’s base emitter voltage, so that no calibration

is required. The second measurement channel measures the

output of an on-chip temperature sensor, to monitor the tem-

perature of the device and its environment.

The ADM1023 communicates over a 2-wire serial interface

compatible with SMBus standards. Under and over tempera-

ture limits can be programmed into the device over the serial

bus, and an

ALERT output signals when the on-chip or remote

temperature is out of range. This output can be used as an

interrupt, or as an SMBus alert.

*Patents pending.

Pentium is a registered trademark of Intel Corporation.

ON-CHIP

TEMPERATURE

SENSOR

A-TO-D

CONVERTER

BUSY

RUN/STANDBY

EXTERNAL DIODE OPEN-CIRCUIT

ADDRESS POINTER

REGISTER

ONE-SHOT

REGISTER

CONVERSION RATE

REGISTER

OFFSET

REGISTERS

REMOTE TEMPERATURE

HIGH-LIMIT REGISTERS

CONFIGURATION

REGISTER

INTERRUPT

MASKING

SMBUS INTERFACE

LOCAL TEMPERATURE

LOW-LIMIT COMPARATOR

LOCAL TEMPERATURE

HIGH-LIMIT COMPARATOR

REMOTE TEMPERATURE

LOW-LIMIT COMPARATOR

REMOTE TEMPERATURE

HIGH-LIMIT COMPARATOR

REMOTE TEMPERATURE

VALUE REGISTERS

LOCAL TEMPERATURE

VALUE REGISTER

STATUS REGISTER

NC

GND

NC

GND

NC

NC

NC

SDATA

SCLK

ADD0

ADD1

ALERT

STBY

D+

D–

REMOTE TEMPERATURE

LOW-LIMIT REGISTERS

LOCAL TEMPERATURE

HIGH-LIMIT REGISTER

LOCAL TEMPERATURE

LOW-LIMIT REGISTER

ANALOG

MUX

NC = NO CONNECT

ADM1023