1 Features

• Accurately Senses Die Temperature of Remote

ICs or Diode Junctions

• Uses TruTherm Technology for Precision “Thermal

Diode” Temperature Measurement

• Thermal Diode Input Stage with Analog Filtering

• Thermal Diode Digital Filtering

• Intel Pentium 4 Processor on 90nm Process or

2N3904 Non-ideality Selection

• Remote Diode Fault Detection

• On-board Local Temperature Sensing

• Remote Temperature Readings Without Digital

Filtering:

– 0.125°C LSb

– 10-bits Plus Sign or 11-bits Programmable

Resolution

– 11-bits Resolves Temperatures Above

127 °C

• Remote Temperature Readings with Digital

Filtering:

– 0.03125°C LSb with Filtering

– 12-bits Plus Sign or 13-bits Programmable

Resolution

– 13-bits Resolves Temperatures Above

127°C

• Local Temperature Readings:

– 0.25°C

– 9-bits Plus Sign

• Status Register Support

• Programmable Conversion Rate Allows User

Optimization of Power Consumption

• Shutdown Mode One-shot Conversion Control

• SMBus 2.0 Compatible Interface, Supports

TIMEOUT

• 8-pin VSSOP Package

• Key Specifications:

– Remote Temperature Accuracy ±0.75°C (max)

– Local Temperature Accuracy ±3.0°C (max)

– Supply Voltage 3.0V to 3.6V

– Supply Current 402μA (typ)

2 Applications

• Processor/Computer System Thermal

Management

– e.g. Laptop, Desktop, Workstations, Server)

• Electronic Test Equipment

• Office Electronics

3 Description

The LM95231 is a precision dual remote diode

temperature sensor (RDTS) that uses Texas

Instruments' TruTherm technology. The 2-wire serial

interface of the LM95231 is compatible with SMBus

2.0. The LM95231 can sense three temperature

zones, it can measure the temperature of its own

die as well as two diode connected transistors.

The LM95231 includes digital filtering and an

advanced input stage that includes analog filtering

and TruTherm technology that reduces processor-toprocessor

non-ideality spread. The diode connected

transistors can be a “thermal diode” as found in

Intel and AMD processors or can simply be a

diode connected MMBT3904 transistor. TruTherm

technology allows accurate measurement of “thermal

diodes” found on small geometry processes, 90nm

and below. The LM95231 supports user selectable

thermal diode non-ideality of either a Pentium 4

processor on 90nm process or 2N3904.

The LM95231 resolution format for remote

temperature readings can be programmed to be

11-bits signed or unsigned with the digital filtering

disabled. When the filtering is enabled the resolution

increases to 13-bits signed or unsigned. In the

unsigned mode the LM95231 remote diode readings

can resolve temperatures above 127°C. Local

temperature readings have a resolution of 9-bits plus

sign.