LM35/LM35A/LM35C/LM35CA/LM35D 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. The LM35 does not require any external calibration or trimming to provide typical accuracies of g (/4§ C at room temperature and g */4§ C over a full b55 to a 150§ C 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 mA 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 b55§ to a 150§ C temperature range, while the LM35C is rated for a b40§ to a 110§ C range (b10§ with improved accuracy). The LM35 series is available packaged 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 and a plastic TO-202 package. Features Y Y Y Y Y Y Y Y Y Y Y Calibrated directly in § Celsius (Centigrade) Linear a 10.0 mV/§ C scale factor 0.5§ C accuracy guaranteeable (at a 25§ C) Rated for full b55§ to a 150§ C range Suitable for remote applications Low cost due to wafer-level trimming Operates from 4 to 30 volts Less than 60 mA current drain Low self-heating, 0.08§ C in still air Nonlinearity only g (/4§ C typical Low impedance output, 0.1 X for 1 mA load Connection Diagrams TO-92 Plastic Package TO-46 Metal Can Package* SO-8 Small Outline Molded Package TL/H/5516 – 2 TL/H/5516–1 *Case is connected to negative pin (GND) Order Number LM35H, LM35AH, LM35CH, LM35CAH or LM35DH See NS Package Number H03H TO-202 Plastic Package TL/H/5516 – 21 Order Number LM35CZ, LM35CAZ or LM35DZ See NS Package Number Z03A Top View N.C. e No Connection Order Number LM35DM See NS Package Number M08A Typical Applications TL/H/5516 – 3 FIGURE 1. Basic Centigrade Temperature Sensor ( a 2§ C to a 150§ C) TL/H/5516 – 4 Choose R1 e b VS/50 mA VOUT e a 1,500 mV at a 150§ C e a 250 mV at a 25§ C TL/H/5516–24 Order Number LM35DP See NS Package Number P03A eb 550 mV at b 55§ C FIGURE 2. Full-Range Centigrade Temperature Sensor TRI-STATEÉ is a registered trademark of National Semiconductor Corporation. C1995 National Semiconductor Corporation TL/H/5516 RRD-B30M75/Printed in U. S. A. LM35/LM35A/LM35C/LM35CA/LM35D Precision Centigrade Temperature Sensors December 1994 Absolute Maximum Ratings (Note 10) SO Package (Note 12): If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Supply Voltage Vapor Phase (60 seconds) 215§ C Infrared (15 seconds) 220§ C ESD Susceptibility (Note 11) 2500V Specified Operating Temperature Range: TMIN to TMAX (Note 2) b 55§ C to a 150§ C LM35, LM35A b 40§ C to a 110§ C LM35C, LM35CA LM35D 0§ C to a 100§ C a 35V to b 0.2V a 6V to b 1.0V Output Voltage Output Current 10 mA b 60§ C to a 180§ C Storage Temp., TO-46 Package, b 60§ C to a 150§ C TO-92 Package, b 65§ C to a 150§ C SO-8 Package, b 65§ C to a 150§ C TO-202 Package, Lead Temp.: TO-46 Package, (Soldering, 10 seconds) 300§ C TO-92 Package, (Soldering, 10 seconds) 260§ C a 230§ C TO-202 Package, (Soldering, 10 seconds) Electrical Characteristics (Note 1) (Note 6) LM35A Parameter Accuracy (Note 7) Conditions TA e a 25§ C TA eb10§ C TA e TMAX TA e TMIN Typical Tested Limit (Note 4) g 0.2 g 0.5 g 0.2 g 0.5 Design Limit (Note 5) Units (Max.) g 0.4 g 1.0 g 0.4 g 0.4 g 1.0 g 0.4 g 1.5 g 0.15 g 0.3 §C a 10.0 a 9.9, a 10.1 mV/§ C g 0.18 Sensor Gain (Average Slope) TMINsTAsTMAX a 10.0 a 9.9, a 10.1 Load Regulation (Note 3) 0sILs1 mA TA e a 25§ C TMINsTAsTMAX g 0.4 g 1.0 g 0.5 Line Regulation (Note 3) TA e a 25§ C 4VsVSs30V g 0.02 Quiescent Current (Note 9) VS e a 5V, a 25§ C VS e a 5V VS e a 30V, a 25§ C VS e a 30V 56 105 56.2 105.5 Temperature Coefficient of Quiescent Current Tested Limit (Note 4) g 0.3 TMINsTAsTMAX 4VsVSs30V, a 25§ C 4VsVSs30V Typical §C §C §C §C g 0.3 Nonlinearity (Note 8) Change of Quiescent Current (Note 3) LM35CA Design Limit (Note 5) g 0.01 g 0.35 g 0.4 g 3.0 g 0.5 g 0.1 g 0.02 g 0.05 g 0.01 133 56 91 56.2 91.5 2.0 0.2 0.5 a 0.39 a 0.5 a 2.0 0.2 0.5 Minimum Temperature for Rated Accuracy In circuit of Figure 1 , IL e 0 a 1.5 Long Term Stability TJ e TMAX, for 1000 hours g 0.08 67 131 68 1.0 g 1.0 g 1.0 g 1.0 g 3.0 mV/mA mV/mA g 0.1 mV/V mV/V g 0.05 67 116 mA mA mA mA 2.0 mA mA a 0.39 a 0.5 mA/§ C a 1.5 a 2.0 §C g 0.08 114 68 1.0 §C Note 1: Unless otherwise noted, these specifications apply: b 55§ C s TJ s a 150§ C for the LM35 and LM35A; b 40§ s TJ s a 110§ C for the LM35C and LM35CA; and 0§ s TJ s a 100§ C for the LM35D. VS e a 5Vdc and ILOAD e 50 mA, in the circuit of Figure 2. These specifications also apply from a 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-202 package is 85§ C/W junction to ambient. For additional thermal resistance information see table in the Applications section. 2 Electrical Characteristics (Note 1) (Note 6) (Continued) LM35 Parameter Accuracy, LM35, LM35C (Note 7) Conditions TA e a 25§ C TA eb10§ C TA e TMAX TA e TMIN Typical Tested Limit (Note 4) g 0.4 g 1.0 g 0.5 g 0.8 g 1.5 g 0.8 g 1.5 Accuracy, LM35D (Note 7) TA e a 25§ C TA e TMAX TA e TMIN Nonlinearity (Note 8) TMINsTAsTMAX g 0.3 Sensor Gain (Average Slope) TMINsTAsTMAX a 10.0 a 9.8, a 10.2 Load Regulation (Note 3) 0sILs1 mA TA e a 25§ C TMINsTAsTMAX g 0.4 g 2.0 g 0.5 Line Regulation (Note 3) TA e a 25§ C 4VsVSs30V g 0.02 Quiescent Current (Note 9) VS e a 5V, a 25§ C VS e a 5V VS e a 30V, a 25§ C VS e a 30V 56 105 56.2 105.5 Change of Quiescent Current (Note 3) 4VsVSs30V, a 25§ C 4VsVSs30V Temperature Coefficient of Quiescent Current LM35C, LM35D Design Limit (Note 5) Typical Tested Limit (Note 4) g 0.4 g 1.0 g 0.5 g 1.5 g 0.8 g 1.5 g 0.8 g 0.6 g 2.0 g 1.5 g 0.01 g 0.9 g 2.0 g 0.5 §C a 10.0 a 9.8, a 10.2 mV/§ C g 0.4 g 0.5 g 0.2 g 0.02 g 0.01 161 56 91 56.2 91.5 3.0 0.2 0.5 a 0.39 a 0.7 a 2.0 0.2 0.5 Minimum Temperature for Rated Accuracy In circuit of Figure 1 , IL e 0 a 1.5 Long Term Stability TJ e TMAX, for 1000 hours g 0.08 80 158 82 2.0 §C §C §C §C g 0.2 g 5.0 g 0.1 Units (Max.) §C §C §C g 0.9 g 0.5 Design Limit (Note 5) g 2.0 g 2.0 g 5.0 mV/mA mV/mA g 0.2 mV/V mV/V g 0.1 80 141 mA mA mA mA 3.0 mA mA a 0.39 a 0.7 mA/§ C a 1.5 a 2.0 §C g 0.08 138 82 2.0 §C 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 kX 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. 3 Typical Performance Characteristics Thermal Resistance Junction to Air Thermal Time Constant Thermal Response in Still Air Thermal Response in Stirred Oil Bath Minimum Supply Voltage vs. Temperature Quiescent Current vs. Temperature (In Circuit of Figure 1 .) TL/H/5516 – 17 Quiescent Current vs. Temperature (In Circuit of Figure 2 .) Accuracy vs. Temperature (Guaranteed) Accuracy vs. Temperature (Guaranteed) TL/H/5516 – 18 Noise Voltage Start-Up Response TL/H/5516 – 22 4 Applications The TO-46 metal package can also be soldered to a metal surface or pipe without damage. Of course, in that case the Vb 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 lightweight 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. 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 the surface 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. Temperature Rise of LM35 Due To Self-heating (Thermal Resistance) Still air Moving air Still oil Stirred oil (Clamped to metal, Infinite heat sink) TO-46, TO-46, TO-92, TO-92, SO-8 SO-8 TO-202 TO-202 *** no heat sink small heat fin* no heat sink small heat fin** no heat sink small heat fin** no heat sink small heat fin 100§ C/W 180§ C/W 140§ C/W 220§ C/W 110§ C/W 85§ C/W 60§ C/W 400§ C/W 40§ C/W 90§ C/W 70§ C/W 105§ C/W 90§ C/W 25§ C/W 40§ C/W 100§ C/W 40§ C/W 90§ C/W 70§ C/W 100§ C/W 30§ C/W 45§ C/W 40§ C/W 50§ C/W (24§ C/W) (55§ C/W) (23§ 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 (/16× printed circuit board with 2 oz. foil or similar. Typical Applications (Continued) TL/H/5516 – 19 FIGURE 3. LM35 with Decoupling from Capacitive Load TL/H/5516 – 20 FIGURE 4. LM35 with R-C Damper 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 VIN to ground and a series R-C damper such as 75X in series with 0.2 or 1 mF from output to ground are often useful. These are shown in Figures 13, 14, and 16. 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 200X load resistor as shown in Figure 5, 6, or 8, it is relatively immune to wiring 5 Typical Applications (Continued) TL/H/5516 – 6 FIGURE 6. Two-Wire Remote Temperature Sensor (Output Referred to Ground) TL/H/5516–5 FIGURE 5. Two-Wire Remote Temperature Sensor (Grounded Sensor) TL/H/5516–7 FIGURE 7. Temperature Sensor, Single Supply, b55§ to a 150§ C TL/H/5516 – 8 FIGURE 8. Two-Wire Remote Temperature Sensor (Output Referred to Ground) TL/H/5516–9 FIGURE 9. 4-To-20 mA Current Source (0§ C to a 100§ C) TL/H/5516 – 10 FIGURE 10. Fahrenheit Thermometer 6 Typical Applications (Continued) TL/H/5516– 11 FIGURE 11. Centigrade Thermometer (Analog Meter) TL/H/5516 – 12 FIGURE 12. Expanded Scale Thermometer (50§ to 80§ Fahrenheit, for Example Shown) TL/H/5516 – 13 FIGURE 13. Temperature To Digital Converter (Serial Output) ( a 128§ C Full Scale) TL/H/5516 – 14 FIGURE 14. Temperature To Digital Converter (Parallel TRI-STATEÉ Outputs for Standard Data Bus to mP Interface) (128§ C Full Scale) 7 Typical Applications (Continued) TL/H/5516 – 16 * e 1% or 2% film resistor -Trim RB for VB e 3.075V -Trim RC for VC e 1.955V -Trim RA for VA e 0.075V a 100mV/§ C c Tambient -Example, VA e 2.275V at 22§ C FIGURE 15. Bar-Graph Temperature Display (Dot Mode) TL/H/5516 – 15 FIGURE 16. LM35 With Voltage-To-Frequency Converter And Isolated Output (2§ C to a 150§ C; 20 Hz to 1500 Hz) 8 Block Diagram TL/H/5516 – 23 9 Physical Dimensions inches (millimeters) 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 10 Physical Dimensions inches (millimeters) (Continued) Power Package TO-202 (P) Order Number LM35DP NS Package Number P03A 11 LM35/LM35A/LM35C/LM35CA/LM35D Precision Centigrade Temperature Sensors Physical Dimensions inches (millimeters) (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 OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation 2900 Semiconductor Drive P.O. Box 58090 Santa Clara, CA 95052-8090 Tel: 1(800) 272-9959 TWX: (910) 339-9240 National Semiconductor GmbH Livry-Gargan-Str. 10 D-82256 F4urstenfeldbruck Germany Tel: (81-41) 35-0 Telex: 527649 Fax: (81-41) 35-1 National Semiconductor Japan Ltd. Sumitomo Chemical Engineering Center Bldg. 7F 1-7-1, Nakase, Mihama-Ku Chiba-City, Ciba Prefecture 261 Tel: (043) 299-2300 Fax: (043) 299-2500 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Hong Kong Ltd. 13th Floor, Straight Block, Ocean Centre, 5 Canton Rd. Tsimshatsui, Kowloon Hong Kong Tel: (852) 2737-1600 Fax: (852) 2736-9960 National Semiconductores Do Brazil Ltda. Rue Deputado Lacorda Franco 120-3A Sao Paulo-SP Brazil 05418-000 Tel: (55-11) 212-5066 Telex: 391-1131931 NSBR BR Fax: (55-11) 212-1181 National Semiconductor (Australia) Pty, Ltd. Building 16 Business Park Drive Monash Business Park Nottinghill, Melbourne Victoria 3168 Australia Tel: (3) 558-9999 Fax: (3) 558-9998 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.