Rainbow Electronics LM86 - Manual

LM86
± 0.75˚C Accurate, Remote Diode and Local Digital
Temperature Sensor with Two-Wire Interface
General Description
The LM86 is an 11-bit digital temperature sensor with a
2-wire System Management Bus (SMBus) serial interface.
The LM86 accurately measures its own temperature as well
as the temperature of an external device, such as processor
thermal diode or diode connected transistor such as the
2N3904. The temperature of any ASIC can be accurately
determined using the LM86 as long as a dedicated diode
(semiconductor junction) is available on the target die. The
LM86 remote sensor accuracy of
± 0.75˚C is factory trimmed
for the 1.008 typical non-ideality factor of the mobile Pen-
tium
™ III thermal diode. The LM86 has an Offset
register to allow measuring other diodes without
requiring continuous software management. Contact
hardware.monitor.team @ nsc.com to obtain the latest data for
new processors.
Activation of the ALERT output occurs when any tempera-
ture goes outside a preprogrammed window set by the HIGH
and LOW temperature limit registers or exceeds the T_CRIT
temperature limit. Activation of the T_CRIT_A occurs when
any temperature exceeds the T_CRIT programmed limit.
The LM86 is pin and register compatible with the the Analog
Devices ADM1032 and Maxim MAX6657/8.
Features
n Accurately senses die temperature of remote ICs or
diode junctions
n Offset register allows sensing a variety of thermal
diodes accurately
n On-board local temperature sensing
n 10 bit plus sign remote diode temperature data format,
0.125 ˚C resolution
n T_CRIT_A output useful for system shutdown
n ALERT output supports SMBus 2.0 protocol
n SMBus 2.0 compatible interface, supports TIMEOUT
n 8-pin MSOP and SOIC packages
Key Specifications
j Supply Voltage 3.0V to 3.6V
j Supply Current 0.8mA (typ)
j Local Temp Accuracy (includes quantization error)
T
A
=25˚C to 125˚C ± 3.0˚C (max)
j Remote Diode Temp Accuracy (includes quantization
error)
T
A
=30˚C, T
D
=80˚C ± 0.75˚C (max)
T
A
=30˚C to 50˚C, T
D
=60˚C to 100˚C ± 1.0˚C (max)
T
A
=0˚C to 85˚C, T
D
=25˚C to 125˚C ± 3.0˚C (max)
Applications
n Computer System Thermal Management
(e.g. Laptop, Desktop, Workstations, Server)
n Electronic Test Equipment
n Office Electronics
Simplified Block Diagram
10130301
Pentium ™ is a trademark of Intel Corporation.
April 2003
LM86
±
0.75˚C
Accurate,
Remote
Diode
and
Local
Digital
T
emperature
Sensor
with
T
wo-W
ire
Interface
© 2003 National Semiconductor Corporation DS101303 www.national.com