March 13, 2008
LM95245
Precision Remote Diode Digital Temperature Sensor with
TruTherm® BJT Beta Compensation Technology for 45nm
Process
Digital filter for remote channel
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General Description
Programmable TCRIT and OS thresholds
The LM95245 is an 11-bit digital temperature sensor with a
Programmable shared hysteresis register
2-wire System Management Bus (SMBus) interface and
TruTherm technology that can monitor the temperature of a
remote diode as well as its own temperature. The LM95245
can be used to very accurately monitor the temperature of
external devices such as microprocessors. TruTherm tech-
nology allows the LM95245 to precisely monitor thermal
diodes found in 90 nm and smaller geometry processes. The
LM95245 is specifically targeted for Intel processors on 45nm
process. LM95245 reports temperature in two different for-
mats for +127.875°C/-128°C range and 0°C/255°C range.
The LM95245 T_CRIT and OS outputs are asserted when
either unmasked channel exceeds its programmed limit and
can be used to shutdown the system, to turn on the system
fans, or as a microcontroller interrupt function. The current
status of the T_CRIT and OS pins can be read back from the
status registers via the SMBus interface. All limits have a
shared programmable hysteresis register.
Diode Fault Detection
Mask, Offset, and Status Registers
SMBus 2.0 compatible interface, supports TIMEOUT
Programmable conversion rate for best power
consumption
Three-level address pin
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Standby mode one-shot conversion control
Pin-for-pin compatible with the LM95235 and LM86/LM89/
LM99
8-pin MSOP and SOP packages
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Key Specifications
■ꢀSupply Voltage
3.0 V to 3.6 V
350 µA (typ)
■ꢀSupply Current, Conv. Rate = 1 Hz
■ꢀRemote Diode Temperature Accuracy
ꢀTA = 25°C to 85°C; TD = 50°C to 105°C
ꢀTA = 25°C to 85°C; TD = 40°C to 125°C
■ꢀLocal Temperature Accuracy
ꢀTA = 25°C to 100°C
The remote temperature channel of the LM95245 has a pro-
grammable digital filter. The LM95245 is targeted for a typical
Intel® processor on a 45 nm, 65 nm or 90nm process, and
has an offset register for maximum flexibility and best accu-
racy.
±0.75°C (max)
±1.5°C (max)
The LM95245 has a three-level address pin to connect up to
3 devices to the same SMBus master, that is shared with the
OS output. The LM95245 has a programmable conversion
rate register and a standby mode to save power. One con-
version can be triggered in standby mode by writing to the
one-shot register.
±2.0°C (max)
16 to 0.4 Hz
■ꢀConversion Rate, Both Channels
Applications
Processor/Computer System Thermal Management
(e.g. Laptops, Desktops, Workstations, Servers)
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Features
Remote and Local temperature channels
Electronic Test Equipment
Office Electronics
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Targeted for Intel 45nm processor diodes
Two Formats: −128°C to +127.875°C and
0°C to 255.875°C
Connection Diagram
MSOP-8 and SOP-8
30015102
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TruTherm® is a registered trademark of National Semiconductor Corporation.
Intel® is a registered trademark of Intel Corporation.
Pentium® is a registered trademark of Intel Corporation.
© 2008 National Semiconductor Corporation
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