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LM35
Precision Centigrade Temperature Sensors
LM35 Precision Centigrade Temperature Sensors
November 2000
General Description
The LM35 series are precision integrated-circuit temperature
sensors, whose output voltage is linearly proportional to the
Celsius (Centigrade) temperature. The LM35 thus has an
advantage over linear temperature sensors calibrated in
˚ Kelvin, as the user is not required to subtract a large
constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external
calibration or trimming to provide typical accuracies of
at room temperature and
temperature range. Low cost is assured by trimming and
calibration at the wafer level. The LM35’s low output impedance, linear output, and precise inherent calibration make
interfacing to readout or control circuitry especially easy. It
can be used with single power supplies, or with plus and
minus supplies. As it draws only 60 µA from its supply, it has
very low self-heating, less than 0.1˚C in still air. The LM35 is
rated to operate over a −55˚ to +150˚C temperature range,
while the LM35C is rated for a −40˚ to +110˚C range (−10˚
with improved accuracy). The LM35 series isavailable pack-
3
±
⁄4˚C over a full −55 to +150˚C
1
±
⁄4˚C
Typical Applications
aged in hermetic TO-46 transistor packages, while the
LM35C, LM35CA, and LM35D are also available in the
plastic TO-92 transistor package. The LM35D is also available in an 8-lead surface mount small outline package anda
plastic TO-220 package.
Features
n Calibrated directly in ˚ Celsius (Centigrade)
n Linear + 10.0 mV/˚C scale factor
n 0.5˚C accuracy guaranteeable (at +25˚C)
n Rated for full −55˚ to +150˚C range
n Suitable for remote applications
n Low cost due to wafer-level trimming
n Operates from 4 to 30 volts
n Less than 60 µA current drain
n Low self-heating, 0.08˚C in still air
n Nonlinearity only
n Low impedance output, 0.1 Ω for 1 mA load
1
±
⁄4˚C typical
DS005516-4
DS005516-3
FIGURE 1. Basic Centigrade Temperature Sensor
(+2˚C to +150˚C)
FIGURE 2. Full-Range Centigrade Temperature Sensor
© 2000 National Semiconductor Corporation DS005516 www.national.com
Choose R1=−VS/50 µA
=+1,500 mV at +150˚C
V
OUT
= +250 mV at +25˚C
= −550 mV at −55˚C
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Connection Diagrams
LM35
TO-46
Metal Can Package*
DS005516-1
*Case is connected to negative pin (GND)
Order Number LM35H, LM35AH, LM35CH, LM35CAH or
LM35DH
See NS Package Number H03H
TO-92
Plastic Package
DS005516-2
Order Number LM35CZ,
LM35CAZ or LM35DZ
See NS Package Number Z03A
SO-8
Small Outline Molded Package
DS005516-21
N.C. = No Connection
Top View
Order Number LM35DM
See NS Package Number M08A
TO-220
Plastic Package*
DS005516-24
*Tab is connected to the negative pin (GND).
Note: The LM35DT pinout is different than the discontinued LM35DP.
Order Number LM35DT
See NS Package Number TA03F
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Page 3
LM35
Absolute Maximum Ratings (Note 10)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage +35V to −0.2V
Output Voltage +6V to −1.0V
Output Current 10 mA
Storage Temp.;
TO-46 Package, −60˚C to +180˚C
TO-92 Package, −60˚C to +150˚C
TO-92 and TO-220 Package,
(Soldering, 10 seconds) 260˚C
SO Package (Note 12)
Vapor Phase (60 seconds) 215˚C
Infrared (15 seconds) 220˚C
ESD Susceptibility (Note 11) 2500V
Specified Operating Temperature Range: T
(Note 2)
MIN
to T
MAX
LM35, LM35A −55˚C to +150˚C
LM35C, LM35CA −40˚C to +110˚C
LM35D 0˚C to +100˚C
SO-8 Package, −65˚C to +150˚C
TO-220 Package, −65˚C to +150˚C
Lead Temp.:
TO-46 Package,
(Soldering, 10 seconds) 300˚C
Electrical Characteristics
(Notes 1, 6)
LM35A LM35CA
Parameter Conditions Tested Design Tested Design Units
Typical Limit Limit Typical Limit Limit (Max.)
(Note 4) (Note 5) (Note 4) (Note 5)
Accuracy T
(Note 7) T
Nonlinearity T
=+25˚C
A
=−10˚C
A
T
A=TMAX
T
A=TMIN
MIN≤TA≤TMAX
±
±
±
±
±
0.2
0.3
0.4
0.4
0.18
(Note 8)
Sensor Gain T
MIN≤TA≤TMAX
+10.0 +9.9, +10.0 +9.9, mV/˚C
(Average Slope) +10.1 +10.1
Load Regulation T
(Note 3) 0≤I
≤1mA T
L
Line Regulation T
=+25˚C
A
MIN≤TA≤TMAX
=+25˚C
A
(Note 3) 4V≤V
Quiescent Current V
(Note 9) V
S
=+5V 105 131 91 114 µA
S
V
S
V
=+30V 105.5 133 91.5 116 µA
S
Change of 4V≤V
Quiescent Current 4V≤V
≤30V
S
=+5V, +25˚C 56 67 56 67 µA
=+30V, +25˚C 56.2 68 56.2 68 µA
≤30V, +25˚C 0.2 1.0 0.2 1.0 µA
S
≤30V 0.5 2.0 0.5 2.0 µA
S
±
±
±
±
0.4
0.5
0.01
0.02
(Note 3)
Temperature +0.39 +0.5 +0.39 +0.5 µA/˚C
Coefficient of
Quiescent Current
Minimum Temperature In circuit of +1.5 +2.0 +1.5 +2.0 ˚C
for Rated Accuracy
Long Term Stability T
Figure 1
J=TMAX
,IL=0
, for
±
0.08
1000 hours
±
±
±
±
±
0.05
0.5
1.0
1.0
1.0
±
±
±
0.35
3.0
0.1
±
0.2
±
0.3
±
0.4
±
0.4
±
0.15
±
0.4
±
0.5
±
0.01
±
0.02
±
0.08 ˚C
±
0.5 ˚C
±
1.0 ˚C
±
1.0 ˚C
±
1.5 ˚C
±
0.3 ˚C
±
1.0 mV/mA
±
3.0 mV/mA
±
0.05 mV/V
±
0.1 mV/V
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Electrical Characteristics
LM35
(Notes 1, 6)
LM35 LM35C, LM35D
Parameter Conditions Tested Design Tested Design Units
Typical Limit Limit Typical Limit Limit (Max.)
(Note 4) (Note 5) (Note 4) (Note 5)
Accuracy, T
LM35, LM35C T
(Note 7) T
Accuracy, LM35D
(Note 7)
Nonlinearity T
=+25˚C
A
=−10˚C
A
A=TMAX
T
A=TMIN
T
=+25˚C
A
T
A=TMAX
T
A=TMIN
MIN≤TA≤TMAX
±
0.4
±
0.5
±
0.8
±
0.8
±
0.3
±
1.0
±
1.5
±
1.5
±
0.5
±
0.4
±
0.5
±
0.8
±
0.8
±
0.6
±
0.9
±
0.9
±
0.2
±
1.0 ˚C
±
1.5 ˚C
±
1.5 ˚C
±
2.0 ˚C
±
1.5 ˚C
±
2.0 ˚C
±
2.0 ˚C
±
0.5 ˚C
(Note 8)
Sensor Gain T
MIN≤TA≤TMAX
+10.0 +9.8, +10.0 +9.8, mV/˚C
(Average Slope) +10.2 +10.2
Load Regulation T
(Note 3) 0≤I
≤1mA T
L
Line Regulation T
=+25˚C
A
MIN≤TA≤TMAX
=+25˚C
A
(Note 3) 4V≤V
Quiescent Current V
(Note 9) V
S
=+5V 105 158 91 138 µA
S
V
S
V
=+30V 105.5 161 91.5 141 µA
S
Change of 4V≤V
Quiescent Current 4V≤V
±
0.4
±
0.5
±
0.01
≤30V
S
±
0.02
=+5V, +25˚C 56 80 56 80 µA
=+30V, +25˚C 56.2 82 56.2 82 µA
≤30V, +25˚C 0.2 2.0 0.2 2.0 µA
S
≤30V 0.5 3.0 0.5 3.0 µA
S
±
2.0
±
5.0
±
0.1
±
0.2
±
±
±
±
0.4
0.5
0.01
0.02
±
2.0 mV/mA
±
5.0 mV/mA
±
0.1 mV/V
±
0.2 mV/V
(Note 3)
Temperature +0.39 +0.7 +0.39 +0.7 µA/˚C
Coefficient of
Quiescent Current
Minimum Temperature In circuit of +1.5 +2.0 +1.5 +2.0 ˚C
for Rated Accuracy
Long Term Stability T
Figure 1
J=TMAX
,IL=0
, for
±
0.08
±
0.08 ˚C
1000 hours
Note 1: Unless otherwise noted, these specifications apply: −55˚C≤TJ≤+150˚C for the LM35 and LM35A; −40˚≤TJ≤+110˚C for the LM35C and LM35CA; and
≤+100˚C for the LM35D. VS=+5Vdc and I
0˚≤T
J
Specifications in boldface apply over the full rated temperature range.
Note 2: Thermal resistance of the TO-46 package is 400˚C/W, junction to ambient, and 24˚C/W junction to case. Thermal resistance of the TO-92 package is
180˚C/W junction to ambient. Thermal resistance of the small outline molded package is 220˚C/W junction to ambient. Thermal resistance of the TO-220 package
is 90˚C/W junction to ambient. For additional thermal resistance information see table in theApplications section.
Note 3: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output due to heating effects can be
computed by multiplying the internal dissipation by the thermal resistance.
Note 4: Tested Limits are guaranteed and 100% tested in production.
Note 5: Design Limits are guaranteed (but not 100% production tested) over the indicated temperature and supply voltage ranges. These limits are not used to
calculate outgoing quality levels.
Note 6: Specifications in boldface apply over the full rated temperature range.
Note 7: Accuracy is defined as the error between the output voltage and 10mv/˚C times the device’s case temperature, at specified conditions of voltage, current,
and temperature (expressed in ˚C).
Note 8: Nonlinearity is defined as the deviation of the output-voltage-versus-temperature curve from the best-fit straight line, over the device’s rated temperature
range.
Note 9: Quiescent current is defined in the circuit of
Note 10: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its rated operating conditions. See Note 1.
Note 11: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Note 12: See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” or the section titled “Surface Mount” found in a current National
Semiconductor Linear Data Book for other methods of soldering surface mount devices.
=50 µA, in the circuit of
LOAD
Figure 1
.
Figure 2
. These specifications also apply from +2˚C to T
in the circuit of
MAX
Figure 1
.
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Typical Performance Characteristics
LM35
Thermal Resistance
Junction to Air
Thermal Response in
Stirred Oil Bath
DS005516-25
Thermal Time Constant
Minimum Supply
Voltage vs. Temperature
DS005516-26
Thermal Response
in Still Air
Quiescent Current
vs. Temperature
(In Circuit of
Figure 1
DS005516-27
.)
Quiescent Current
vs. Temperature
(In Circuit of
Figure 2
.)
DS005516-28
DS005516-31
Accuracy vs. Temperature
(Guaranteed)
DS005516-29
DS005516-32
DS005516-30
Accuracy vs. Temperature
(Guaranteed)
DS005516-33
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Typical Performance Characteristics (Continued)
LM35
Noise Voltage
DS005516-34
Applications
The LM35 can be applied easily in the same way as other
integrated-circuit temperature sensors. It can be glued or
cemented to a surface and its temperature will be within
about 0.01˚C of the surface temperature.
This presumes that the ambient air temperature is almost the
same as the surface temperature; if the air temperature were
much higher or lower than the surface temperature, the
actual temperature of the LM35 die would be at an intermediate temperature between the surface temperature and the
air temperature. This is expecially true for the TO-92 plastic
package, where the copper leads are the principal thermal
path to carry heat into the device, so its temperature might
be closer to the air temperature than to thesurface temperature.
To minimize this problem, be sure that the wiring to the
LM35, as it leaves the device, is held at the same temperature as the surface of interest. The easiest way to do this is
to cover up these wires with a bead of epoxy which will
insure that the leads and wires are all at the same temperature as the surface, and that the LM35 die’s temperature will
not be affected by the air temperature.
Start-Up Response
DS005516-35
The TO-46 metal package can also be soldered to a metal
surface or pipe without damage. Of course, in that case the
V− terminal of the circuit will be grounded to that metal.
Alternatively, the LM35 can be mounted inside a sealed-end
metal tube, and can then be dipped into a bath or screwed
into a threaded hole in a tank. As with any IC, the LM35 and
accompanying wiring and circuits must be kept insulated and
dry, to avoid leakage and corrosion. This is especially true if
the circuit may operate at cold temperatures where condensation can occur.Printed-circuit coatings and varnishes such
as Humiseal and epoxy paints or dips are often used to
insure that moisture cannot corrode the LM35 or its connections.
These devices are sometimes soldered to a small
light-weight heat fin, to decrease the thermal time constant
and speed up the response in slowly-moving air. On the
other hand, a small thermal mass may be added to the
sensor,to give the steadiest reading despite small deviations
in the air temperature.
Temperature Rise of LM35 Due To Self-heating (Thermal Resistance,θJA)
TO-46, TO-46*, TO-92, TO-92**, SO-8 SO-8** TO-220
no heat
sink
Still air 400˚C/W 100˚C/W 180˚C/W 140˚C/W 220˚C/W 110˚C/W 90˚C/W
Moving air 100˚C/W 40˚C/W 90˚C/W 70˚C/W 105˚C/W 90˚C/W 26˚C/W
Still oil 100˚C/W 40˚C/W 90˚C/W 70˚C/W
Stirred oil 50˚C/W 30˚C/W 45˚C/W 40˚C/W
(Clamped to metal,
Infinite heat sink) (24˚C/W) (55˚C/W)
*Wakefield type 201, or 1" disc of 0.020" sheet brass, soldered to case, or similar.
**TO-92 and SO-8 packages glued and leads soldered to 1" square of 1/16" printed circuit board with 2 oz. foil or similar.
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small heat fin no heat
sink
small heat fin no heat
sink
small heat fin no heat
sink
Page 7
Typical Applications
DS005516-19
FIGURE 3. LM35 with Decoupling from Capacitive Load
DS005516-20
FIGURE 4. LM35 with R-C Damper
CAPACITIVE LOADS
Like most micropower circuits, the LM35 has a limited ability
to drive heavy capacitive loads. The LM35 by itself is able to
drive 50 pf without special precautions. If heavier loads are
anticipated, it is easy to isolate or decouple the load with a
resistor; see
capacitance with a series R-C damper from output to
ground; see
When the LM35 is applied with a 200Ω load resistor as
shown in
to wiring capacitance because the capacitance forms a bypass from ground to input, not on the output. However, as
with any linear circuit connected to wires in a hostile environment, its performance can be affected adversely by intense electromagnetic sources such as relays, radio transmitters, motors with arcing brushes, SCR transients, etc, as
its wiring can act as a receiving antenna and its internal
junctions can act as rectifiers. For best results in such cases,
a bypass capacitor from V
damper such as 75Ω in series with 0.2 or 1µF from output to
ground are often useful. These are shown in
Figure 14
Figure 3
Figure 4
. Or you can improve the tolerance of
.
Figure 5,Figure 6orFigure 8
to ground and a series R-C
IN
, and
Figure 16
.
it is relatively immune
Figure 13
LM35
DS005516-6
FIGURE 6. Two-Wire Remote Temperature Sensor
(Output Referred to Ground)
DS005516-7
FIGURE 7. Temperature Sensor, Single Supply, −55˚ to
+150˚C
,
DS005516-5
FIGURE 5. Two-Wire Remote Temperature Sensor
(Grounded Sensor)
DS005516-8
FIGURE 8. Two-Wire Remote Temperature Sensor
(Output Referred to Ground)
DS005516-9
FIGURE 9. 4-To-20 mA Current Source (0˚C to +100˚C)
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Typical Applications (Continued)
LM35
FIGURE 10. Fahrenheit Thermometer
DS005516-11
FIGURE 11. Centigrade Thermometer (Analog Meter)
DS005516-10
DS005516-12
FIGURE 12. Fahrenheit ThermometerExpanded Scale
Thermometer
(50˚ to 80˚ Fahrenheit, for Example Shown)
FIGURE 13. Temperature To Digital Converter (Serial Output) (+128˚C Full Scale)
FIGURE 14. Temperature To Digital Converter (Parallel TRI-STATE™Outputs for
Standard Data Bus to µP Interface) (128˚C Full Scale)
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DS005516-13
DS005516-14
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Typical Applications (Continued)
LM35
*
=1% or 2% film resistor
for VB=3.075V
Trim R
B
for VC=1.955V
Trim R
C
for VA=0.075V + 100mV/˚C x T
Trim R
A
Example, VA=2.275V at 22˚C
DS005516-16
ambient
FIGURE 15. Bar-Graph Temperature Display (Dot Mode)
DS005516-15
FIGURE 16. LM35 With Voltage-To-Frequency Converter And Isolated Output
(2˚C to +150˚C; 20 Hz to 1500 Hz)
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Block Diagram
LM35
DS005516-23
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Physical Dimensions inches (millimeters) unless otherwise noted
TO-46 Metal Can Package (H)
Order Number LM35H, LM35AH, LM35CH,
LM35CAH, or LM35DH
NS Package Number H03H
LM35
SO-8 Molded Small Outline Package (M)
Order Number LM35DM
NS Package Number M08A
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
LM35
Power Package TO-220 (T)
Order Number LM35DT
NS Package Number TA03F
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
LM35 Precision Centigrade Temperature Sensors
TO-92 Plastic Package (Z)
Order Number LM35CZ, LM35CAZ or LM35DZ
NS Package Number Z03A
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accordance with instructions for use provided in the
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can be reasonably expected to cause the failure of
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