Main Power Supply

LM89

SMBus

Master

MCU/

GPU/

ASIC/

FPGA

2.2nF*

Core Voltage

D+

D-

SMBData

SMBCLK

Shutdown Control

3.3V derived

from Aux.

Supply

*Note: 2.2nF capacitor must be placed as close as possible to D+ and D- pins of the LM89.

T_CRIT_A

ALERT

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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

1

•

Accurately Senses Die Temperature of Remote

a 2-wire System Management Bus (SMBus) serial

ICs or Diode Junctions

interface. The LM89 accurately measures its own

•

Offset Register Allows Accurate Sensing of a

temperature as well as the temperature of an external

Variety of Thermal Diodes

device, such as processor thermal diode or diode-

connected transistor such as the 2N3904. The

•

On-Board Local Temperature Sensing

temperature of any ASIC, GPU, FPGA or MCU can

•

10-Bit Plus Sign Remote Diode Temperature Data

be accurately determined using the LM89 as long as

Format, 0.125°C Resolution

a

dedicated

diode

(semiconductor

junction)

is

•

T_CRIT_A Output Useful for System Shutdown

available on the target die. The LM89 has an Offset

•

ALERT Output Supports SMBus 2.0 Protocol

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

•

8-Pin VSSOP and SOIC Packages

set by the HIGH and LOW limit registers or exceeds

•

Key Specifications:

the T_CRIT limit. Activation of the T_CRIT_A occurs

–

Supply Voltage: 3.0 V to 3.6 V

when

any

temperature

exceeds

the

T_CRIT

programmed limit.

–

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.

–

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

2 Applications

versions are 85°C. (See Device Comparison Table.)

•

Processor/Computer System Thermal

Management

Device Information(1)

(For Example, Laptop, Desktop, Workstations,

PART NUMBER

PACKAGE

BODY SIZE (NOM)

Server)

LM89-1D

VSSOP (8)

3.0 mm x 3.0 mm

•

Electronic Test Equipment

LM89C

SOIC (8)

4.9 mm x 3.9 mm

•

Office Electronics

(1) For all available packages, see the orderable addendum at

the end of the datasheet.

4 Remote Diode Temperature Sensor System Diagram

T_CRIT_A Temperature Response Diagram

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.