LM84 datasheet(2/18 Pages) TI

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LM84

Diode Input Digital Temperature Sensor with Two-Wire

Interface

General Description

The

LM84

remote

diode

temperature

sensor,

Delta-Sigma

analog-to-digital

converter,

and

digital

over-temperature detector with an SMBus™ interface. The

LM84 senses its own temperature as well as the tempera-

ture of a target IC with a diode junction, such as a Pentium®

II processor or a diode connected 2N3904. A diode junction

(semiconductor junction) is required on the target IC’s die. A

host can query the LM84 at any time to read the temperature

of this diode as well as the temperature state of the LM84

itself. A T_CRIT_A interrupt output becomes active when the

temperature is greater than a programmable comparator

limit, T_CRIT.

The host can program as well as read back the state of the

T_CRIT register. Three state logic inputs allow two pins

(ADD0, ADD1) to select up to 9 SMBus address locations for

the LM84. The sensor powers up with default thresholds of

127˚C for T_CRIT.

Features

Directly senses die temperature of remote ICs

Senses temperature of remote diodes

SMBus compatible interface, supports SMBus Timeout

7 bit plus sign temperature data format

2 address select lines enable 9 LM84s to be connected

to a single bus

Key Specifications

j Supply Voltage

3.0V - 3.6V

j Supply Current

1 mA (max)

j Local Temperature Accuracy

±1.0˚C (typ)

j Remote Diode Temperature Accuracy

+60˚C to +100˚C

±3˚C (max)

0˚C to +125˚C

±5˚C (max)

Applications

System Thermal Management

Personal Computers

Electronic Test Equipment

Office Electronics

HVAC

Simplified Block Diagram

SMBus™ is a trademark of the Intel Corporation.

Pentium® II processor is a registered trademark of the Intel Corporation.

I2C® is a registered trademark of the Philips Corporation.

DS100961-1

# Indicates Active Low (”NOT“)

July 2000

DS100961

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