LM35DZ/LFT4 - NATIONAL SEMICONDUCTOR

LM35

LM35 Precision Centigrade Temperature Sensors

Literature Number: SNIS159B

LM35

Precision Centigrade Temperature Sensors

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 Centi-

grade scaling. The LM35 does not require any external

calibration or trimming to provide typical accuracies of ±

⁄

˚C

at room temperature and ±

⁄

˚C over a full −55 to +150˚C

temperature range. Low cost is assured by trimming and

calibration at the wafer level. The LM35’s low output imped-

ance, 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 is available pack-

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 avail-

able in an 8-lead surface mount small outline package and a

plastic TO-220 package.

Features

nCalibrated directly in ˚ Celsius (Centigrade)

nLinear + 10.0 mV/˚C scale factor

n0.5˚C accuracy guaranteeable (at +25˚C)

nRated for full −55˚ to +150˚C range

nSuitable for remote applications

nLow cost due to wafer-level trimming

nOperates from 4 to 30 volts

nLess than 60 µA current drain

nLow self-heating, 0.08˚C in still air

nNonlinearity only ±

⁄

˚C typical

nLow impedance output, 0.1 Ωfor 1 mA load

Typical Applications

DS005516-3

FIGURE 1. Basic Centigrade Temperature Sensor

(+2˚C to +150˚C)

DS005516-4

Choose R1=−V

/50 µA

VOUT=+1,500 mV at +150˚C

= +250 mV at +25˚C

= −550 mV at −55˚C

FIGURE 2. Full-Range Centigrade Temperature Sensor

November 2000

LM35 Precision Centigrade Temperature Sensors

Connection Diagrams

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

LM35

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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

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

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

MIN

to T

MAX

(Note 2)

LM35, LM35A −55˚C to +150˚C

LM35C, LM35CA −40˚C to +110˚C

LM35D 0˚C to +100˚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

=+25˚C ±0.2 ±0.5 ±0.2 ±0.5 ˚C

(Note 7) T

=−10˚C ±0.3 ±0.3 ±1.0 ˚C

MAX

±0.4 ±1.0 ±0.4 ±1.0 ˚C

MIN

±0.4 ±1.0 ±0.4 ±1.5 ˚C

Nonlinearity T

MIN

≤T

MAX

±0.18 ±0.35 ±0.15 ±0.3 ˚C

(Note 8)

Sensor Gain T

MIN

≤T

MAX

+10.0 +9.9, +10.0 +9.9, mV/˚C

(Average Slope) +10.1 +10.1

Load Regulation T

=+25˚C ±0.4 ±1.0 ±0.4 ±1.0 mV/mA

(Note 3) 0≤I

≤1mA T

MIN

≤T

MAX

±0.5 ±3.0 ±0.5 ±3.0 mV/mA

Line Regulation T

=+25˚C ±0.01 ±0.05 ±0.01 ±0.05 mV/V

(Note 3) 4V≤V

≤30V ±0.02 ±0.1 ±0.02 ±0.1 mV/V

Quiescent Current V

=+5V, +25˚C 56 67 56 67 µA

(Note 9) V

=+5V 105 131 91 114 µA

=+30V, +25˚C 56.2 68 56.2 68 µA

=+30V 105.5 133 91.5 116 µA

Change of 4V≤V

≤30V, +25˚C 0.2 1.0 0.2 1.0 µA

Quiescent Current 4V≤V

≤30V 0.5 2.0 0.5 2.0 µA

(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

Figure 1

Long Term Stability T

MAX

, for ±0.08 ±0.08 ˚C

1000 hours

LM35

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Electrical Characteristics

(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

=+25˚C ±0.4 ±1.0 ±0.4 ±1.0 ˚C

LM35, LM35C T

=−10˚C ±0.5 ±0.5 ±1.5 ˚C

(Note 7) T

MAX

±0.8 ±1.5 ±0.8 ±1.5 ˚C

MIN

±0.8 ±1.5 ±0.8 ±2.0 ˚C

Accuracy, LM35D

(Note 7) T

=+25˚C ±0.6 ±1.5 ˚C

MAX

±0.9 ±2.0 ˚C

MIN

±0.9 ±2.0 ˚C

Nonlinearity T

MIN

≤T

MAX

±0.3 ±0.5 ±0.2 ±0.5 ˚C

(Note 8)

Sensor Gain T

MIN

≤T

MAX

+10.0 +9.8, +10.0 +9.8, mV/˚C

(Average Slope) +10.2 +10.2

Load Regulation T

=+25˚C ±0.4 ±2.0 ±0.4 ±2.0 mV/mA

(Note 3) 0≤I

≤1mA T

MIN

≤T

MAX

±0.5 ±5.0 ±0.5 ±5.0 mV/mA

Line Regulation T

=+25˚C ±0.01 ±0.1 ±0.01 ±0.1 mV/V

(Note 3) 4V≤V

≤30V ±0.02 ±0.2 ±0.02 ±0.2 mV/V

Quiescent Current V

=+5V, +25˚C 56 80 56 80 µA

(Note 9) V

=+5V 105 158 91 138 µA

=+30V, +25˚C 56.2 82 56.2 82 µA

=+30V 105.5 161 91.5 141 µA

Change of 4V≤V

≤30V, +25˚C 0.2 2.0 0.2 2.0 µA

Quiescent Current 4V≤V

≤30V 0.5 3.0 0.5 3.0 µA

(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

Figure 1

Long Term Stability T

MAX

, 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

0˚≤TJ≤+100˚C for the LM35D. VS=+5Vdc and ILOAD=50 µA, in the circuit of

Figure 2

. These specifications also apply from +2˚C to TMAX in the circuit of

Figure 1

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 the Applications 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

Figure 1

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 kΩresistor.

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.

LM35

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Typical Performance Characteristics

Thermal Resistance

Junction to Air

DS005516-25

Thermal Time Constant

DS005516-26

Thermal Response

in Still Air

DS005516-27

Thermal Response in

Stirred Oil Bath

DS005516-28

Minimum Supply

Voltage vs. Temperature

DS005516-29

Quiescent Current

vs. Temperature

(In Circuit of

Figure 1

DS005516-30

Quiescent Current

vs. Temperature

(In Circuit of

Figure 2

DS005516-31

Accuracy vs. Temperature

(Guaranteed)

DS005516-32

Accuracy vs. Temperature

(Guaranteed)

DS005516-33

LM35

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Typical Performance Characteristics (Continued)

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 interme-

diate 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 the surface tempera-

ture.

To minimize this problem, be sure that the wiring to the

LM35, as it leaves the device, is held at the same tempera-

ture 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 tempera-

ture as the surface, and that the LM35 die’s temperature will

not be affected by the air temperature.

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 conden-

sation 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 connec-

tions.

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,θ

)

TO-46, TO-46*, TO-92, TO-92**, SO-8 SO-8** TO-220

no heat

sink small heat fin 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.

Noise Voltage

DS005516-34

Start-Up Response

DS005516-35

LM35

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Typical Applications

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

Figure 3

. Or you can improve the tolerance of

capacitance with a series R-C damper from output to

ground; see

Figure 4

When the LM35 is applied with a 200Ωload resistor as

shown in

Figure 5

Figure 6

Figure 8

it is relatively immune

to wiring capacitance because the capacitance forms a by-

pass from ground to input, not on the output. However, as

with any linear circuit connected to wires in a hostile envi-

ronment, its performance can be affected adversely by in-

tense electromagnetic sources such as relays, radio trans-

mitters, 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

to ground and a series R-C

damper such as 75Ωin series with 0.2 or 1 µF from output to

ground are often useful. These are shown in

Figure 13

Figure 14

, and

Figure 16

DS005516-19

FIGURE 3. LM35 with Decoupling from Capacitive Load

DS005516-20

FIGURE 4. LM35 with R-C Damper

DS005516-5

FIGURE 5. Two-Wire Remote Temperature Sensor

(Grounded Sensor)

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

DS005516-8

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)

LM35

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Typical Applications (Continued)

DS005516-10

FIGURE 10. Fahrenheit Thermometer

DS005516-11

FIGURE 11. Centigrade Thermometer (Analog Meter)

DS005516-12

FIGURE 12. Fahrenheit ThermometerExpanded Scale

Thermometer

(50˚ to 80˚ Fahrenheit, for Example Shown)

DS005516-13

FIGURE 13. Temperature To Digital Converter (Serial Output) (+128˚C Full Scale)

DS005516-14

FIGURE 14. Temperature To Digital Converter (Parallel TRI-STATE™Outputs for

Standard Data Bus to µP Interface) (128˚C Full Scale)

LM35

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Typical Applications (Continued)

DS005516-16

*=1% or 2% film resistor

Trim RBfor VB=3.075V

Trim RCfor VC=1.955V

Trim RAfor VA=0.075V + 100mV/˚C x Tambient

Example, VA=2.275V at 22˚C

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)

LM35

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Block Diagram

DS005516-23

LM35

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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

SO-8 Molded Small Outline Package (M)

Order Number LM35DM

NS Package Number M08A

LM35

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

Power Package TO-220 (T)

Order Number LM35DT

NS Package Number TA03F

LM35

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

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www.national.com

TO-92 Plastic Package (Z)

Order Number LM35CZ, LM35CAZ or LM35DZ

NS Package Number Z03A

LM35 Precision Centigrade Temperature Sensors

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.

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