LM95234
Quad Remote Diode and Local Temperature Sensor with
SMBus Interface and TruTherm
TM
Technology
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.
The LM95234 reports temperature in two different formats
for +127.875C/128C range and 0C/255C 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.
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.
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.
Features
n
Accurately senses die temperature of 4 remote ICs or
diode junctions and local temperature
n
TruTherm technology accurately senses sub-micron
process thermal diodes
n
Programmable digital filters and analog front end filter
n
0.125C LSb temperature resolution
n
0.03125C LSb remote temperature resolution with
digital filter enabled
n
+127.875C/128C and 0C/255C 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
Key Specifications
j
Local Temperature Accuracy
2.0 C (max)
j
Remote Diode Temperature
Accuracy
0.75 C (max)
j
Supply Voltage
3.0 V to 3.6 V
j
Average Supply Current (1Hz
conversion rate)
0.5 mA (typ)
Applications
n
Processor/Computer System Thermal Management
(e.g. Laptop, Desktop, Workstations, Server)
n
Electronic Test Equipment
n
Office Electronics
Connection Diagram
LLP-14
20106301
TOP VIEW
TruTherm
TM
is a trademark of National Semiconductor Corporation.
ADVANCE INFORMATION
August 2006
LM95234
Quad
Remote
Diode
and
Local
T
emperature
Sensor
with
SMBus
Interface
and
T
ruTherm
T
echnology
2006 National Semiconductor Corporation
DS201063
www.national.com
Ordering Information
Part Number
Package
Marking
NS Package
Number
Transport
Media
LM95234CISD
95234CI
SDA14B (LLP-14)
1000 Units on Tape and Reel
LM95234CISDX
95234CI
SDA14B (LLP-14)
4500 Units on Tape and Reel
Simplified Block Diagram
20106302
Pin Descriptions
Label
Pin #
Function
Typical Connection
NC
1
No Connect
Not connected. May be left floating, connected to
GND or V
DD
.
V
DD
2
Positive Supply Voltage
Input
DC Voltage from 3.0 V to 3.6 V. V
DD
should be
bypassed with a 0.1F capacitor in parallel with
100pF. The 100pF capacitor should be placed as
close as possible to the power supply pin. Noise
should be kept below 200 mVp-p, a 10 F capacitor
may be required to achieve this.
LM95234
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2
Pin Descriptions
(Continued)
Label
Pin #
Function
Typical Connection
D4+
3
Diode Current Source
To fourth Diode Anode. Connected to remote
discrete diode-connected transistor junction or to the
diode-connected transistor junction on a remote IC
whose die temperature is being sensed. A capacitor
is not required between D4+ and D-. A 100 pF
capacitor between D4+ and D- can be added and
may improve perfomance in noisy systems. Float
this pin if this thermal diode is not used.
D3+
4
Diode Current Source
To third Diode Anode. Connected to remote discrete
diode-connected transistor junction or to the
diode-connected transistor junction on a remote IC
whose die temperature is being sensed. A capacitor
is not required between D3+ and D-. A 100 pF
capacitor between D3+ and D- can be added and
may improve perfomance in noisy systems. Float
this pin if this thermal diode is not used.
D-
5
Diode Return Current Sink
To all Diode Cathodes. Common D- pin for all four
remote diodes.
D2+
6
Diode Current Source
To second Diode Anode. Connected to remote
discrete diode-connected transistor junction or to the
diode-connected transistor junction on a remote IC
whose die temperature is being sensed. A capacitor
is not required between D2+ and D-. A 100 pF
capacitor between D2+ and D- can be added and
may improve perfomance in noisy systems. Float
this pin if this thermal diode is not used.
D1+
7
Diode Current Source
To first Diode Anode. Connected to remote discrete
diode-connected transistor junction or to the
diode-connected transistor junction on a remote IC
whose die temperature is being sensed. A capacitor
is not required between D1+ and D-. A 100 pF
capacitor between D1+ and D- can be added and
may improve perfomance in noisy systems. Float
this pin if this thermal diode is not used.
GND
8
Power Supply Ground
System low noise ground.
A0
9
Dgital Input
SMBus slave address select pin. Selects one of
three addresses. Can be tied to V
DD
, GND, or to the
middle of a resistor divider connected between V
DD
and GND.
TCRIT1
10
Digital Output, Open-Drain
Critical temperature output 1. Requires pull-up
resistor. Active "LOW".
TCRIT2
11
Digital Output, Open-Drain
Critical temperature output 2. Requires pull-up
resistor. Active "LOW".
SMBDAT
12
SMBus Bi-Directional Data
Line, Open-Drain Output
From and to Controller; may require an external
pull-up resistor
SMBCLK
13
SMBus Clock Input
From Controller; may require an external pull-up
resistor
TCRIT3
14
Digital Output, Open-Drain
Critical temperature output 3. Requires pull-up
resistor. Active "LOW".
LM95234
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3
Typical Application
20106303
LM95234
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4
Physical Dimensions
inches (millimeters)
unless otherwise noted
14-Lead Molded Leadless Leadframe Package (LLP),
Order Number LM95234CISD or LM95234CISDX
NS Package Number SDA14B
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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www.national.com
LM95234
Quad
Remote
Diode
and
Local
T
emperature
Sensor
with
SMBus
Interface
and
T
ruTherm
T
echnology
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