LM95231 TruTherm Precision Dual Remote Diode Temperature Sensor with SMBus Interface
鈩?/div>
Precision Dual Remote Diode Temperature
Sensor with SMBus Interface
General Description
The LM95231 is a precision dual remote diode temperature
sensor (RDTS) that uses National鈥檚 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 non-
ideality processor to processor spread. The diode connected
transistors can be a 鈥渢hermal diode鈥?as found in Intel and
AMD processors or can simply be a diode connected
MMBT3904 transistor. TruTherm technology allows accurate
measurement of 鈥渢hermal diodes鈥?found on small geometry
processes, 90nm and below. The LM95231 supports user
selectable thermal diode non-ideality of either a Pentium
廬
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processor in the 90nm process or 2N3904.
The LM95231 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 LM95231 remote diode
readings can resolve temperatures above 127藲C. Local tem-
perature readings have a resolution of 9-bits plus sign.
n
Remote temperature readings without digital filtering:
鈥?0.125 藲C LSb
鈥?10-bits plus sign or 11-bits programmable resolution
鈥?11-bits resolves temperatures above 127 藲C
n
Remote temperature readings with digital filtering:
鈥?0.03125 藲C LSb with filtering
鈥?12-bits plus sign or 13-bits programmable resolution
鈥?13-bits resolves temperatures above 127 藲C
n
Local temperature readings:
鈥?0.25 藲C
鈥?9-bits plus sign
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Status register support
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Programmable conversion rate allows user optimization
of power consumption
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Shutdown mode one-shot conversion control
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SMBus 2.0 compatible interface, supports TIMEOUT
n
8-pin MSOP package
Key Specifications
j
Remote Diode Temperature Accuracy
T
A
=30藲C to 50藲C, T
D
=45藲C to 85藲C
j
Local Temperature Accuracy
鹵
0.75 藲C (max)
鹵
2.0 藲C (max)
T
A
=0藲C to 85藲C, T
D
=25藲C to 140藲C
T
A
=0藲C to 85藲C
Features
n
Accurately senses die temperature of remote ICs or
diode junctions
n
Uses TruTherm technology for precision 鈥渢hermal diode鈥?/div>
temperature measurement
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Thermal diode input stage with analog filtering
n
Thermal diode digital filtering
n
Pentium 4 90nm or 2N3904 non-ideality selection
n
Remote diode fault detection
n
On-board local temperature sensing
j
Supply Voltage
j
Supply Current
鹵
3.0 藲C (max)
3.0 V to 3.6 V
2 mA (typ)
Applications
n
Processor/Computer System Thermal Management
(e.g. Laptop, Desktop, Workstations, Server)
n
Electronic Test Equipment
n
Office Electronics
Connection Diagram
MSOP-8
20120202
TOP VIEW
TruTherm
鈩?/div>
is a trademark of National Semiconductor Corporation.
I2C
廬
is a registered trademark of Phillips Corporation.
Pentium
鈩?/div>
is a trademark of Intel Corporation.
漏 2005 National Semiconductor Corporation
DS201202
www.national.com
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