LM83 Triple-Diode Input and Local Digital Temperature Sensor with Two-Wire Interface
November 1999
LM83
Triple-Diode Input and Local Digital Temperature Sensor
with Two-Wire Interface
General Description
The LM83 is a digital temperature sensor with a 2 wire serial
interface that senses the voltage and thus the temperature of
three remote diodes using a Delta-Sigma analog-to-digital
converter with a digital over-temperature detector. The LM83
accurately senses its own temperature as well as the tem-
perature of three external devices, such as Pentium II
®
Pro-
cessors or diode connected 2N3904s. The temperature of
any ASIC can be detected using the LM83 as long as a dedi-
cated diode (semiconductor junction) is available on the die.
Using the SMBus interface a host can access the LM83’s
registers at any time. Activation of a T_CRIT_A output oc-
curs when any temperature is greater than a programmable
comparator limit, T_CRIT. Activation of an INT output occurs
when any temperature is greater than its corresponding pro-
grammable comparator HIGH limit.
The host can program as well as read back the state of the
T_CRIT register and the four T_HIGH registers. Three state
logic inputs allow two pins (ADD0, ADD1) to select up to 9
SMBus address locations for the LM83. The sensor powers
up with default thresholds of 127˚C for T_CRIT and all
T_HIGHs. The LM83 is pin for pin and register compatible
with the LM84 as well as the Maxim MAX1617 and the Ana-
log Devices ADM1021.
n
On-board local temperature sensing
n
SMBus and I
2
C compatible interface, supports
SMBus 1.1 TIMEOUT
n
Two interrupt outputs: INT and T_CRIT_A
n
Register readback capability
n
7 bit plus sign temperature data format, 1 ˚C resolution
n
2 address select pins allow connection of 9 LM83s on a
single bus
Key Specifications
n
Supply Voltage
n
Supply Current
0˚C to +85˚C
3.0V to 3.6V
0.8mA (max)
n
Local Temp Accuracy (includes quantization error)
±
3.0˚C (max)
n
Remote Diode Temp Accuracy (includes quantization
error)
+25˚C to +100˚C
0˚C to +125˚C
±
3˚C (max)
±
4˚C (max)
Applications
n
n
n
n
n
System Thermal Management
Computers
Electronic Test Equipment
Office Electronics
HVAC
Features
n
Accurately senses die temperature of 3 remote ICs, or
diode junctions
Simplified Block Diagram
DS101058-1
SMBus
™
is a trademark of the Intel Corporation.
Pentium II
®
is a registered trademark of the Intel Corporation.
I2C
®
is a registered trademark of the Philips Corporation.
© 1999 National Semiconductor Corporation
DS101058
www.national.com
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