ADVANCE INFORMATION
August 2006
LM95234
Quad Remote Diode and Local Temperature Sensor with
™
SMBus Interface and TruTherm Technology
n TruTherm technology accurately senses sub-micron
process thermal diodes
General Description
LM95234 is an 11-bit digital temperature sensor with a 2-wire
System Management Bus (SMBus) interface that can moni-
tor the temperature of four remote diodes as well as its own
temperature. The LM95234 can be used to very accurately
monitor the temperature of up to four external devices such
as microprocessors, graphics processors or diode-
connected 2N3904s. The LM95234’s TruTherm technology
allows sensing of 90nm or 65nm process thermal diodes
accurately.
n Programmable digital filters and analog front end filter
n 0.125˚C LSb temperature resolution
n 0.03125˚C LSb remote temperature resolution with
digital filter enabled
n
+127.875˚C/–128˚C and 0˚C/255˚C remote ranges
n Remote diode fault detection, model selection and offset
correction
n Mask and status register support
n 3 programmable TCRIT outputs with programmable
shared hysteresis and Fault-Queue
n Programmable conversion rate and shutdown mode
one-shot conversion control
n SMBus 2.0 compatible interface, supports TIMEOUT
n Three-level address pin
n 14-pin LLP package
The LM95234 reports temperature in two different formats
for +127.875˚C/–128˚C range and 0˚C/255˚C range. The
LM95234 TCRIT1, TCRIT2 and TCRIT3 outputs are trig-
gered when any unmasked channel exceeds its correspond-
ing programmable 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 TCRIT1, TCRIT2
and TCRIT3 pins can be read back from the status registers.
Mask registers are available for further control of the TCRIT
outputs.
Key Specifications
Two LM95234 remote temperature channels have program-
mable digital filters while the other two remote channels
utilize a fault-queue to minimize unwanted TCRIT events
when temperature spikes are encountered.
j
Local Temperature Accuracy
2.0 ˚C (max)
0.75 ˚C (max)
j
Remote Diode Temperature
Accuracy
j
j
Supply Voltage
3.0 V to 3.6 V
0.5 mA (typ)
For optimum flexibility and accuracy, each LM95234 channel
includes registers for sub-micron process or 2N3904 diode
model selection as well as offset correction. A three level
address pin allows connection of up to 3 LM95234s to the
same SMBus master. The LM95234 includes power saving
functions such as: programmable conversion rate, shutdown
mode, and turn off of unused channels.
Average Supply Current (1Hz
conversion rate)
Applications
n Processor/Computer System Thermal Management
(e.g. Laptop, Desktop, Workstations, Server)
n Electronic Test Equipment
Features
n Office Electronics
n Accurately senses die temperature of 4 remote ICs or
diode junctions and local temperature
Connection Diagram
LLP-14
20106301
TOP VIEW
™
TruTherm is a trademark of National Semiconductor Corporation.
© 2006 National Semiconductor Corporation
DS201063
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