ADM1021AARQ View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
ADM1021AARQ Datasheet PDF : 16 Pages
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a
Low-Cost Microprocessor
System Temperature Monitor*
ADM1021A
FEATURES
Alternative to the ADM1021
On-Chip and Remote Temperature Sensing
No Calibration Necessary
1؇C Accuracy for On-Chip Sensor
3؇C Accuracy for Remote Sensor
Programmable Overtemperature/Undertemperature
Limits
Programmable Conversion Rate
2-Wire SMBus Serial Interface
Supports System Management Bus (SMBus) Alert
200 mA Max Operating Current
1 mA Standby Current
3 V to 5.5 V Supply
Small 16-Lead QSOP Package
APPLICATIONS
Desktop Computers
Notebook Computers
Smart Batteries
Industrial Controllers
Telecom Equipment
Instrumentation
PRODUCT DESCRIPTION
The ADM1021A is a two-channel digital thermometer and
undertemperature/overtemperature alarm, intended for use in
personal computers and other systems requiring thermal monitor-
ing and management. The device can measure the temperature
of a microprocessor using a diode-connected 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 temperature of the device and its environment.
The ADM1021A communicates over a two-wire serial interface
compatible with SMBus standards. Undertemperature and
overtemperature limits can be programmed into the devices 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
ON-CHIP TEMP.
SENSOR
LOCAL TEMPERATURE
VALUE REGISTER
D+
D–
ANALOG MUX
A-TO-D
CONVERTER
BUSY RUN/STANDBY
REMOTE TEMPERATURE
VALUE REGISTER
EXTERNAL DIODE OPEN-CIRCUIT
LOCAL TEMPERATURE
LOW LIMIT COMPARATOR
LOCAL TEMPERATURE
HIGH LIMIT COMPARATOR
REMOTE TEMPERATURE
LOW LIMIT COMPARATOR
REMOTE TEMPERATURE
HIGH LIMIT COMPARATOR
STATUS REGISTER
ADDRESS POINTER
REGISTER
ONE-SHOT
REGISTER
CONVERSION RATE
REGISTER
LOCAL TEMPERATURE
LOW LIMIT REGISTER
LOCAL TEMPERATURE
HIGH LIMIT REGISTER
REMOTE TEMPERATURE
LOW LIMIT REGISTER
REMOTE TEMPERATURE
HIGH LIMIT REGISTER
CONFIGURATION
REGISTER
INTERRUPT
MASKING
STBY
ALERT
ADM1021A
SMBUS INTERFACE
NC VDD NC GND GND NC NC
NC
SDATA
SCLK
ADD0
ADD1
NC = NO CONNECT
*Patents Pending
REV. D
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reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
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Tel: 781/329-4700
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Fax: 781/326-8703 © 2004 Analog Devices, Inc. All rights reserved.
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