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.