1 Features
1• Accurately Senses Die Temperature of Remote
ICs or Diode Junctions
• Offset Register Allows Accurate Sensing of a
Variety of Thermal Diodes diode•
On-Board Local Temperature Sensing
• 10-Bit Plus Sign Remote Diode Temperature Data
Format, 0.125°C Resolution
• T_CRIT_A Output Useful for System Shutdown
• ALERT Output Supports SMBus 2.0 Protocol
• SMBus 2.0 Compatible Interface, Supports
TIMEOUT
• 8-Pin VSSOP and SOIC Packages
• Key Specifications:
– Supply Voltage: 3.0 V to 3.6 V
– Local Temp Accuracy (includes quantization
error)
– TA = 25°C to 125°C ±3.0 °C (max)
– Remote Diode Temp Accuracy (includes
quantization error)
– TA = 30°C, TD = 80°C ±0.75 °C (max)

2 Applications
• Processor/Computer System Thermal
Management
(For Example, Laptop, Desktop, Workstations,
Server)
• Electronic Test Equipment
• Office Electronics

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 a dedicated diode (semiconductor junction) is
available on the target die. The LM89 has an Offset
register to allow calibration for different nonideality
factors without requiring software management.
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.
The LM89 is pin and register compatible with the
LM86, LM90, LM99, On Semiconductor ADM1032
and Maxim MAX6657/8.
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.)