a
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
ACPI-Compliant
High-Accuracy Microprocessor
System Temperature Monitor
ADM1023*
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
®
III; the higher accuracy offered
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.
FUNCTIONAL BLOCK DIAGRAM
ADDRESS POINTER
REGISTER
ONE-SHOT
REGISTER
CONVERSION RATE
REGISTER
OFFSET
REGISTERS
LOCAL TEMPERATURE
VALUE REGISTER
LOCAL TEMPERATURE
LOW-LIMIT COMPARATOR
LOCAL TEMPERATURE
HIGH-LIMIT COMPARATOR
REMOTE TEMPERATURE
LOW-LIMIT COMPARATOR
REMOTE TEMPERATURE
HIGH-LIMIT COMPARATOR
LOCAL TEMPERATURE
LOW-LIMIT REGISTER
LOCAL TEMPERATURE
HIGH-LIMIT REGISTER
REMOTE TEMPERATURE
LOW-LIMIT REGISTERS
REMOTE TEMPERATURE
HIGH-LIMIT REGISTERS
CONFIGURATION
REGISTER
EXTERNAL DIODE OPEN-CIRCUIT
STATUS REGISTER
INTERRUPT
MASKING
ON-CHIP
TEMPERATURE
SENSOR
D+
D–
ANALOG
MUX
A-TO-D
CONVERTER
BUSY
RUN/STANDBY
REMOTE TEMPERATURE
VALUE REGISTERS
STBY
ALERT
ADM1023
SMBUS INTERFACE
NC
V
DD
NC
GND GND
NC
NC
NC
NC = NO CONNECT
SDATA
SCLK
ADD0
ADD1
*Patents
pending.
Pentium is a registered trademark of Intel Corporation.
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
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
AD [ ANALOG DEVICES ]
