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.)