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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

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

⁄

˚C typical

n Low impedance output, 0.1 Ω for 1 mA load

Typical Applications

DS005516-3

FIGURE 1. Basic Centigrade Temperature Sensor

(+2˚C to +150˚C)

DS005516-4

Choose R

=−V

/50 µA

OUT

=+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

Summary of content (13 pages)

PAGE 1
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 Centigrade scaling.
PAGE 2
LM35 Connection Diagrams TO-46 Metal Can Package* SO-8 Small Outline Molded Package DS005516-1 DS005516-21 *Case is connected to negative pin (GND) N.C. = No Connection Order Number LM35H, LM35AH, LM35CH, LM35CAH or LM35DH See NS Package Number H03H Top View Order Number LM35DM See NS Package Number M08A TO-92 Plastic Package TO-220 Plastic Package* DS005516-2 Order Number LM35CZ, LM35CAZ or LM35DZ See NS Package Number Z03A DS005516-24 *Tab is connected to the negative pin (GND).
PAGE 3
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: TMIN 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 If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
PAGE 4
LM35 Electrical Characteristics (Notes 1, 6) LM35 Parameter Conditions Design Limit Limit (Note 4) (Note 5) Typical Accuracy, T A =+25˚C LM35, LM35C T A =−10˚C (Note 7) T A =TMAX ± 0.4 ± 0.5 ± 0.8 ± 0.8 T A =TMIN Accuracy, LM35D (Note 7) LM35C, LM35D Tested ± 1.0 ± 1.5 ± 1.5 T A =+25˚C TA =TMAX TA =TMIN Nonlinearity T MIN≤TA≤TMAX ± 0.3 T MIN≤TA≤TMAX +10.0 ± 0.5 Typical ± 0.4 ± 0.5 ± 0.8 ± 0.8 ± 0.6 ± 0.9 ± 0.9 ± 0.2 Tested Design Units Limit Limit (Max.
PAGE 5
LM35 Typical Performance Characteristics Thermal Resistance Junction to Air Thermal Response in Still Air Thermal Time Constant DS005516-26 DS005516-25 Thermal Response in Stirred Oil Bath DS005516-27 Minimum Supply Voltage vs. Temperature Quiescent Current vs. Temperature (In Circuit of Figure 1.) DS005516-29 DS005516-28 DS005516-30 Quiescent Current vs. Temperature (In Circuit of Figure 2.) Accuracy vs. Temperature (Guaranteed) Accuracy vs.
PAGE 6
LM35 Typical Performance Characteristics (Continued) Noise Voltage Start-Up Response DS005516-34 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.
PAGE 7
LM35 Typical Applications DS005516-19 FIGURE 3. LM35 with Decoupling from Capacitive Load DS005516-6 FIGURE 6. Two-Wire Remote Temperature Sensor (Output Referred to Ground) 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.
PAGE 8
LM35 Typical Applications (Continued) DS005516-11 FIGURE 11. Centigrade Thermometer (Analog Meter) DS005516-10 FIGURE 10. Fahrenheit Thermometer 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) www.
PAGE 9
LM35 Typical Applications (Continued) DS005516-16 * =1% or 2% film resistor Trim RB for VB =3.075V Trim RC for VC =1.955V Trim RA for 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) 9 www.national.
PAGE 10
LM35 Block Diagram DS005516-23 www.national.
PAGE 11
LM35 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 11 www.national.
PAGE 12
LM35 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Power Package TO-220 (T) Order Number LM35DT NS Package Number TA03F www.national.
PAGE 13
LM35 Precision Centigrade Temperature Sensors Physical Dimensions inches (millimeters) unless otherwise noted (Continued) TO-92 Plastic Package (Z) Order Number LM35CZ, LM35CAZ or LM35DZ NS Package Number Z03A LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1.