LM95221
Dual Remote Diode Digital Temperature Sensor with
SMBus Interface
General Description
The LM95221 is a dual remote diode temperature sensor in
an 8-lead MSOP package. The 2-wire serial interface of the
LM95221 is compatible with SMBus 2.0. The LM95221 can
sense three temperature zones, it can measure the tempera-
ture of its own die as well as two diode connected transis-
tors. The diode connected transistors can be a thermal diode
as found in Pentium and AMD processors or can simply be a
diode connected MMBT3904 transistor. The LM95221 reso-
lution format for remote temperature readings can be pro-
grammed to be 10-bits plus sign or 11-bits unsigned. In the
unsigned mode the LM95221 remote diode readings can
resolve temperatures above 127C. Local temperature read-
ings have a resolution of 9-bits plus sign.
The temperature of any ASIC can be accurately determined
using the LM95221 as long as a dedicated diode (semicon-
ductor junction) is available on the target die. The LM95221
remote sensor accuracy of
1C is factory trimmed for a
series resistance of 2.7 ohms and 1.008 non-ideality factor.
Features
n
Accurately senses die temperature of remote ICs or
diode junctions
n
Remote diode fault detection
n
On-board local temperature sensing
n
Remote temperature readings:
-- 0.125 C LSb
-- 10-bits plus sign or 11-bits programmable resolution
-- 11-bits resolves temperatures above 127 C
n
Local temperature readings:
-- 0.25 C
-- 9-bits plus sign
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
Key Specifications
j
Local Temperature Accuracy
T
A
=0C to 85C
3.0 C (max)
j
Remote Diode Temperature Accuracy
T
A
=30C to 50C, T
D
=45C to 85C
1.0 C (max)
T
A
=0C to 85C, T
D
=25C to 140C
3.0 C (max)
j
Supply Voltage
3.0 V to 3.6 V
j
Supply Current
2 mA (typ)
Applications
n
Processor/Computer System Thermal Management
(e.g. Laptop, Desktop, Workstations, Server)
n
Electronic Test Equipment
n
Office Electronics
Simplified Block Diagram
20094301
Pentium
TM
is a trademark of Intel Corporation.
May 2004
LM95221
Dual
Remote
Diode
Digital
T
emperature
Sensor
with
SMBus
Interface
2004 National Semiconductor Corporation
DS200943
www.national.com
Connection Diagram
MSOP-8
20094302
TOP VIEW
Ordering Information
Part Number
Package
Marking
NS Package
Number
Transport
Media
SMBus Device
Address
LM95221CIMM
LM95221CIMM
MUA08A (MSOP-8)
1000 Units on Tape
and Reel
010 1011
LM95221CIMMX
LM95221CIMM
MUA08A (MSOP-8)
3500 Units on Tape
and Reel
010 1011
Pin Descriptions
Label
Pin #
Function
Typical Connection
D1+
1
Diode Current Source
To 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 2.2 nF
diode bypass capacitor is recommended to filter high
frequency noise. Place the 2.2 nF capacitor between
and as close as possible to the LM95221's D+ and
D- pins. Make sure the traces to the 2.2 nF
capacitor are matched. Ground this pin if this
thermal diode is not used.
D1-
2
Diode Return Current Sink
To Diode Cathode. A 2.2 nF capacitor is
recommended between D1+ and D1-. Ground this
pin if this thermal diode is not used.
D2+
3
Diode Current Source
To 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 2.2 nF
diode bypass capacitor is recommended to filter high
frequency noise. Place the 2.2 nF capacitor between
and as close as possible to the LM95221's D+ and
D- pins. Make sure the traces to the 2.2 nF
capacitor are matched. Ground this pin if this
thermal diode is not used.
D2-
4
Diode Return Current Sink
To Diode Cathode. A 2.2 nF capacitor is
recommended between D2+ and D2-. Ground this
pin if this thermal diode is not used.
GND
5
Power Supply Ground
Ground
V
DD
6
Positive Supply Voltage
Input
DC Voltage from 3.0 V to 3.6 V. V
DD
should be
bypassed with a 0.1 F capacitor in parallel with 100
pF. The 100 pF 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.
LM95221
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2
Pin Descriptions
(Continued)
Label
Pin #
Function
Typical Connection
SMBDAT
7
SMBus Bi-Directional Data
Line, Open-Drain Output
From and to Controller; may require an external
pull-up resistor
SMBCLK
8
SMBus Clock Input
From Controller; may require an external pull-up
resistor
Typical Application
20094303
LM95221
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3
Absolute Maximum Ratings
(Note 1)
Supply Voltage
-0.3 V to 6.0 V
Voltage at SMBDAT, SMBCLK
-0.5V to 6.0V
Voltage at Other Pins
-0.3 V to (V
DD
+ 0.3 V)
D- Input Current
1 mA
Input Current at All Other Pins (Note 2)
5 mA
Package Input Current (Note 2)
30 mA
SMBDAT Output Sink Current
10 mA
Storage Temperature
-65C to +150C
Soldering Information, Lead Temperature
MSOP-8 Package (Note 3)
Vapor Phase (60 seconds)
215C
Infrared (15 seconds)
220C
ESD Susceptibility (Note 4)
Human Body Model
2000 V
Machine Model
200 V
Operating Ratings
(Notes 1, 5)
Operating Temperature Range
0C to +115C
Electrical Characteristics
Temperature Range
T
MIN
T
A
T
MAX
LM95221CIMM
0C
T
A
+85C
Supply Voltage Range (V
DD
)
+3.0V to +3.6V
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for V
DD
=+3.0Vdc to 3.6Vdc. Boldface limits apply for T
A
= T
J
=
T
MIN
T
A
T
MAX
; all other limits T
A
= T
J
=+25C, unless otherwise noted. T
J
is the junction temperature of the LM95221. T
D
is the
junction temperature of the remote thermal diode.
Parameter
Conditions
Typical
Limits
Units
(Note 6)
(Note 7)
(Limit)
Accuracy Using Local Diode
T
A
= 0C to +85C, (Note 8)
1
3
C (max)
Accuracy Using Remote Diode, see (Note 9) for
Thermal Diode Processor Type.
T
A
= +30C to
+50C
T
D
= +45C
to +85C
1
C (max)
T
A
= +0C to
+85C
T
D
= +25C
to +140C
3
C (max)
Remote Diode Measurement Resolution
11
Bits
0.125
C
Local Diode Measurement Resolution
10
Bits
0.25
C
Conversion Time of All Temperatures at the
Fastest Setting
(Note 11)
66
73
ms (max)
Quiescent Current (Note 10)
SMBus Inactive, 15Hz conversion
rate
2.0
2.6
mA (max)
Shutdown
335
A
D- Source Voltage
0.7
V
Diode Source Current
(D+ - D-)=+ 0.65V; high-level
188
315
A (max)
110
A (min)
Low-level
11.75
20
A (max)
7
A (min)
Low-Level Diode Source Current Variation over
Temperature
T
A
= +30C to +50C
+0.5
A
T
A
= +30C to +85C
+1.5
A
Power-On Reset Threshold
Measure on V
DD
input, falling
edge
2.4
1.8
V (max)
V (min)
LM95221
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4
Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for V
DD
=+3.0 to 3.6 Vdc. Boldface lim-
its apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
=+25C, unless otherwise noted.
Symbol
Parameter
Conditions
Typical
Limits
Units
(Note 6)
(Note 7)
(Limit)
SMBDAT, SMBCLK INPUTS
V
IN(1)
Logical "1" Input Voltage
2.1
V (min)
V
IN(0)
Logical "0"Input Voltage
0.8
V (max)
V
IN(HYST)
SMBDAT and SMBCLK Digital Input
Hysteresis
400
mV
I
IN(1)
Logical "1" Input Current
V
IN
= V
DD
0.005
10
A (max)
I
IN(0)
Logical "0" Input Current
V
IN
= 0 V
-0.005
10
A (max)
C
IN
Input Capacitance
5
pF
SMBDAT OUTPUT
I
OH
High Level Output Current
V
OH
= V
DD
10
A (max)
V
OL
SMBus Low Level Output Voltage
I
OL
= 4mA
I
OL
= 6mA
0.4
0.6
V (max)
SMBus DIGITAL SWITCHING CHARACTERISTICS Unless otherwise noted, these specifications apply for V
DD
=+3.0 Vdc to
+3.6 Vdc, C
L
(load capacitance) on output lines = 80 pF. Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C, unless otherwise noted. The switching characteristics of the LM95221 fully meet or exceed the published specifi-
cations of the SMBus version 2.0. The following parameters are the timing relationships between SMBCLK and SMBDAT sig-
nals related to the LM95221. They adhere to but are not necessarily the SMBus bus specifications.
Symbol
Parameter
Conditions
Typical
Limits
Units
(Note 6)
(Note 7)
(Limit)
f
SMB
SMBus Clock Frequency
100
10
kHz (max)
kHz (min)
t
LOW
SMBus Clock Low Time
from V
IN(0)
max to V
IN(0)
max
4.7
25
s (min)
ms (max)
t
HIGH
SMBus Clock High Time
from V
IN(1)
min to V
IN(1)
min
4.0
s (min)
t
R,SMB
SMBus Rise Time
(Note 12)
1
s (max)
t
F,SMB
SMBus Fall Time
(Note 13)
0.3
s (max)
t
OF
Output Fall Time
C
L
= 400pF,
I
O
= 3mA, (Note 13)
250
ns (max)
t
TIMEOUT
SMBDAT and SMBCLK Time Low for Reset of
Serial Interface (Note 14)
25
35
ms (min)
ms (max)
t
SU;DAT
Data In Setup Time to SMBCLK High
250
ns (min)
t
HD;DAT
Data Out Stable after SMBCLK Low
300
900
ns (min)
ns (max)
t
HD;STA
Start Condition SMBDAT Low to SMBCLK
Low (Start condition hold before the first clock
falling edge)
100
ns (min)
t
SU;STO
Stop Condition SMBCLK High to SMBDAT
Low (Stop Condition Setup)
100
ns (min)
t
SU;STA
SMBus Repeated Start-Condition Setup Time,
SMBCLK High to SMBDAT Low
0.6
s (min)
t
BUF
SMBus Free Time Between Stop and Start
Conditions
1.3
s (min)
LM95221
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