September 2006
LM95241
Dual Remote Diode Temperature Sensor with SMBus
™
Interface and TruTherm Technology (65nm/90nm)
n Remote temperature readings without digital filtering:
General Description
— 0.125 ˚C LSb
The LM95241 is a precision dual remote diode temperature
— 10-bits plus sign or 11-bits programmable resolution
sensor (RDTS) that uses National’s TruTherm technology.
— 11-bits resolves temperatures above 127 ˚C
The 2-wire serial interface of the LM95241 is compatible with
SMBus 2.0. The LM95241 can sense three temperature
n Remote temperature readings with digital filtering:
— 0.03125 ˚C LSb with filtering
zones, it can measure the temperature of its own die as well
— 12-bits plus sign or 13-bits programmable resolution
as two diode connected transistors. The LM95241 includes
— 13-bits resolves temperatures above 127 ˚C
digital filtering and an advanced input stage that includes
n Local temperature readings:
analog filtering and TruTherm technology that reduces
— 0.25 ˚C
processor-to-processor non-ideality spread. The diode con-
— 9-bits plus sign
nected transistors can be a “thermal diode” as found in Intel
and AMD processors or can simply be a diode connected
n Status register support
n Programmable conversion rate allows user optimization
of power consumption
n Shutdown mode one-shot conversion control
n SMBus 2.0 compatible interface, supports TIMEOUT
n 8-pin MSOP package
MMBT3904 transistor. TruTherm technology allows accurate
measurement of “thermal diodes” found on small geometry
processes such as 90nm and 65nm. The LM95241 supports
user selectable thermal diode non-ideality of either Intel
processor on 90nm or 65nm process or 2N3904.
The LM95241 resolution format for remote temperature
readings can be programmed to be 11-bits signed or un-
signed with the digital filtering disabled. When the filtering is
enabled the resolution increases to 13-bits signed or un-
signed. In the unsigned mode the LM95241 remote diode
readings can resolve temperatures above 127˚C. Local tem-
perature readings have a resolution of 9-bits plus sign.
Key Specifications
j
Remote Diode Temperature Accuracy
TA=20˚C to 40˚C, TD=45˚C to 85˚C
TA=0˚C to 85˚C, TD=25˚C to 140˚C
Local Temperature Accuracy
TA=0˚C to 85˚C
1.25 ˚C (max)
2.5 ˚C (max)
j
3.0 ˚C (max)
3.0 V to 3.6 V
471 µA (typ)
Features
j
j
Supply Voltage
n Accurately senses die temperature of remote ICs or
diode junctions
Average Supply Current
n Uses TruTherm technology for precision “thermal diode”
temperature measurement
n Thermal diode input stage with analog filtering
n Thermal diode digital filtering
n Intel processor on 65nm or 90nm process or 2N3904
non-ideality selection
Applications
n Processor/Computer System Thermal Management
(e.g. Laptop, Desktop, Workstations, Server)
n Electronic Test Equipment
n Office Electronics
n Remote diode fault detection
n On-board local temperature sensing
Connection Diagram
MSOP-8
20199702
TOP VIEW
™
TruTherm is a trademark of National Semiconductor Corporation.
I2C® is a registered trademark of Philips Corporation.
Pentium® is a registered trademark of Intel Corporation.
© 2006 National Semiconductor Corporation
DS201997
www.national.com