Datasheet

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.
Features
n Accurately senses die temperature of 3 remote ICs, or
diode junctions
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
j
Supply Voltage 3.0V to 3.6V
j
Supply Current 0.8mA (max)
j
Local Temp Accuracy (includes quantization error)
0˚C to +85˚C
±
3.0˚C (max)
j
Remote Diode Temp Accuracy (includes quantization
error)
+25˚C to +100˚C
±
3˚C (max)
0˚C to +125˚C
±
4˚C (max)
Applications
n System Thermal Management
n Computers
n Electronic Test Equipment
n Office Electronics
n HVAC
Simplified Block Diagram
SMBus
™
is a trademark of the Intel Corporation.
Pentium II
®
is a registered trademark of the Intel Corporation.
I
2
C
®
is a registered trademark of the Philips Corporation.
DS101058-1
November 1999
LM83 Triple-Diode Input and Local Digital Temperature Sensor with Two-Wire Interface
© 2000 National Semiconductor Corporation DS101058 www.national.com