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LM89
SNIS128D –AUGUST 2002–REVISED JUNE 2014
LM89 ±0.75°C Accurate, Remote Diode And Local Digital Temperature Sensor
With Two-Wire Interface
1 Features
3 Description
The LM89 is an 11-bit digital temperature sensor with
a 2-wire System Management Bus (SMBus) serial
interface. The LM89 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, GPU, FPGA or MCU can
be accurately determined using the LM89 as long as
1
•
Accurately Senses Die Temperature of Remote
ICs or Diode Junctions
•
Offset Register Allows Accurate Sensing of a
Variety of Thermal Diodes
•
•
On-Board Local Temperature Sensing
10-Bit Plus Sign Remote Diode Temperature Data
Format, 0.125°C Resolution
a
dedicated diode (semiconductor junction) is
•
•
•
T_CRIT_A Output Useful for System Shutdown
ALERT Output Supports SMBus 2.0 Protocol
available on the target die. The LM89 has an Offset
register to allow calibration for different nonideality
factors without requiring software management.
SMBus 2.0 Compatible Interface, Supports
TIMEOUT
Activation of the ALERT occurs when any
temperature goes outside a preprogrammed window
set by the HIGH and LOW limit registers or exceeds
the T_CRIT limit. Activation of the T_CRIT_A occurs
when any temperature exceeds the T_CRIT
programmed limit.
•
•
8-Pin VSSOP and SOIC Packages
Key Specifications:
–
–
Supply Voltage: 3.0 V to 3.6 V
Local Temp Accuracy (includes quantization
error)
The LM89 is pin and register compatible with the
LM86, LM90, LM99, On Semiconductor ADM1032
and Maxim MAX6657/8.
–
TA = 25°C to 125°C ±3.0 °C (max)
–
Remote Diode Temp Accuracy (includes
quantization error)
The LM89C and the LM89-1C have the same
functions but different SMBus slave addresses,
allowing multiple LM89's on a bus. LM89-1D's default
local T_CRIT temperature limit is 105°C; all other
versions are 85°C. (See Device Comparison Table.)
–
TA = 30°C, TD = 80°C ±0.75 °C (max)
2 Applications
•
Processor/Computer System Thermal
Management
Device Information(1)
(For Example, Laptop, Desktop, Workstations,
Server)
PART NUMBER
LM89-1D
PACKAGE
VSSOP (8)
SOIC (8)
BODY SIZE (NOM)
3.0 mm x 3.0 mm
4.9 mm x 3.9 mm
•
•
Electronic Test Equipment
Office Electronics
LM89C
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
4 Remote Diode Temperature Sensor System Diagram
Main Power Supply
T_CRIT_A Temperature Response Diagram
Core Voltage
Shutdown Control
3.3V derived
from Aux.
Supply
T_CRIT_A
D+
MCU/
GPU/
ASIC/
FPGA
LM89
SMBus
Master
2.2nF*
D-
SMBData
SMBCLK
ALERT
*Note: 2.2nF capacitor must be placed as close as possible to D+ and D- pins of the LM89.
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. UNLESS OTHERWISE NOTED, this document contains ADVANCE
INFORMATION for pre-production products; subject to change without notice.