LM135A

LM135_08 NSC | Alldatasheet

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Technical content

Features

■ Directly calibrated in °Kelvin ■ 1°C initial accuracy available ■ Operates from 400 μA to 5 mA ■ Less than 1Ω dynamic impedance ■ Easily calibrated ■ Wide operating temperature range ■ 200°C overrange ■ Low cost Schematic Diagram 569801 © 2008 National Semiconductor Corporation 5698 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors

Absolute Maximum Ratings (Note 4) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Reverse Current 15 mA Forward Current 10 mA Storage Temperature 8-Pin SOIC Package −65°C to 150°C Specified Operating Temp. Range Continuous Intermittent (Note 2) LM135, LM135A −55°C to 150°C 150°C to 200°C LM235, LM235A −40°C to 125°C 125°C to 150°C LM335, LM335A −40°C to 100°C 100°C to 125°C Lead Temp. (Soldering, 10 seconds) 8-Pin SOIC Package: 300°C Vapor Phase (60 seconds): 215°C Infrared (15 seconds): 220°C Temperature Accuracy (Note 1) LM135/LM235, LM135A/LM235A Parameter Conditions LM135A/LM235A LM135/LM235 Units Min Typ Max Min Typ Max Uncalibrated Temperature Error TC = 25°C, IR = 1 mA 0.5 1 1 3 °C Uncalibrated Temperature Error TMIN ≤ TC ≤ TMAX, IR = 1 mA 1.3 2.7 2 5 °C Temperature Error with 25°C TMIN ≤ TC ≤ TMAX, IR = 1 mA 0.3 1 0.5 1.5 °C Calibration Calibrated Error at Extended TC = TMAX (Intermittent) 2 2 °C Temperatures Non-Linearity IR = 1 mA 0.3 0.5 0.3 1 °C Temperature Accuracy (Note 1) LM335, LM335A Parameter Conditions LM335A LM335 Units Min Typ Max Min Typ Max Uncalibrated Temperature Error TC = 25°C, IR = 1 mA 1 3 2 6 °C Uncalibrated Temperature Error TMIN ≤ TC ≤ TMAX, IR = 1 mA 2 5 4 9 °C Temperature Error with 25°C TMIN ≤ TC ≤ TMAX, IR = 1 mA 0.5 1 1 2 °C Calibration Calibrated Error at Extended TC = TMAX (Intermittent) 2 2 °C Temperatures Non-Linearity IR = 1 mA 0.3 1.5 0.3 1.5 °C Electrical Characteristics (Note 1) LM135/LM235 LM335 Parameter Conditions LM135A/LM235A LM335A Units Min Typ Max Min Typ Max Operating Output Voltage 400 μA ≤ IR ≤ 5 mA 2.5 10 3 14 mV Change with Current At Constant Temperature Dynamic Impedance IR = 1 mA 0.5 0.6 Ω Output Voltage Temperature +10 +10 mV/°C Coefficient Time Constant Still Air 80 80 sec 100 ft/Min Air 10 10 sec Stirred Oil 1 1 sec Time Stability TC = 125°C 0.2 0.2 °C/khr www.national.com 2 LM135/LM235/LM335, LM135A/LM235A/LM335A

Note 1: Accuracy measurements are made in a well-stirred oil bath. For other conditions, self heating must be considered. Note 2: Continuous operation at these temperatures for 10,000 hours for H package and 5,000 hours for Z package may decrease life expectancy of the device. Thermal Resistance 8-Pin SOIC TO-92 TO-46 θJA (Junction to Ambient) 165°C/W 202°C/W 400°C/W θJC (Junction to Case) N/A 170°C/W N/A Note 4: Refer to RETS135H for military specifications. Connection Diagrams 8-Pin SOIC Surface Mount Package 569825 Top View TO-92 Plastic Package 569808 Bottom View TO-46 Metal Can Package* 569826 *Case is connected to negative pin Bottom View

Ordering Information

Package Part Number Package Marking Transport Media NSC Drawing 8-Pin SOIC LM335AM LM335AM 95 Units/Rail M08ALM335AMX 2.5k Units Tape and Reel LM335M LM335M 95 Units/Rail LM335MX 2.5k Units Tape and Reel TO-92 LM335AZ LM335AZ 1800 Bag Z03ZLM335Z LM335Z 1800 Bag TO-46 LM135AH LM135AH 1000 Bag H03H LM135H LM135H 1000 Bag LM235AH LM235AH 1000 Bag LM235H LM235H 1000 Bag LM335AH LM335AH 1000 Bag LM335H LM335H 1000 Bag 3 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A

Typical Performance Characteristics Reverse Voltage Change 569827 Calibrated Error 569828 Reverse Characteristics 569829 Response Time 569830 Dynamic Impedance 569831 Noise Voltage 569832 www.national.com 4 LM135/LM235/LM335, LM135A/LM235A/LM335A

Thermal Resistance Junction to Air 569833 Thermal Time Constant 569834 Thermal Response in Still Air 569835 Thermal Response in Stirred Oil Bath 569836 Forward Characteristics 569837 5 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A

Application Information

Included on the LM135 chip is an easy method of calibrating the device for higher accuracies. A pot connected across the LM135 with the arm tied to the adjustment terminal allows a 1-point calibration of the sensor that corrects for inaccuracy over the full temperature range. This single point calibration works because the output of the LM135 is proportional to absolute temperature with the ex- trapolated output of sensor going to 0V output at 0°K (−273.15°C). Errors in output voltage versus temperature are only slope (or scale factor) errors so a slope calibration at one temperature corrects at all temperatures. The output of the device (calibrated or uncalibrated) can be expressed as: where T is the unknown temperature and T o is a reference temperature, both expressed in degrees Kelvin. By calibrating the output to read correctly at one temperature the output at all temperatures is correct. Nominally the output is calibrated at 10 mV/°K. To insure good sensing accuracy several precautions must be taken. Like any temperature sensing device, self heating can reduce accuracy. The LM135 should be operated at the lowest current suitable for the application. Sufficient current, of course, must be available to drive both the sensor and the calibration pot at the maximum operating temperature as well as any external loads. If the sensor is used in an ambient where the thermal resis- tance is constant, self heating errors can be calibrated out. This is possible if the device is run with a temperature stable current. Heating will then be proportional to zener voltage and therefore temperature. This makes the self heating error pro- portional to absolute temperature the same as scale factor errors. WATERPROOFING SENSORS Meltable inner core heat shrinkable tubing such as manufac- tured by Raychem can be used to make low-cost waterproof sensors. The LM335 is inserted into the tubing about ½″ from the end and the tubing heated above the melting point of the core. The unfilled ½″ end melts and provides a seal over the device. Typical Applications Basic Temperature Sensor 569802 Calibrated Sensor 569809 *Calibrate for 2.982V at 25°C Wide Operating Supply 569810 Minimum Temperature Sensing 569804 Average Temperature Sensing 569818 www.national.com 6 LM135/LM235/LM335, LM135A/LM235A/LM335A

Remote Temperature Sensing 569819 Wire length for 1°C error due to wire drop IR = 1 mA IR = 0.5 mA* AWG FEET FEET 14 4000 8000 16 2500 5000 18 1600 3200 20 1000 2000 22 625 1250 24 400 800 *For IR = 0.5 mA, the trim pot must be deleted. Isolated Temperature Sensor 569820 Simple Temperature Controller 569805 7 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A

Simple Temperature Control 569821 Ground Referred Fahrenheit Thermometer 569822 *Adjust R2 for 2.554V across LM336. Adjust R1 for correct output. Centigrade Thermometer 569823 *Adjust for 2.7315V at output of LM308 www.national.com 8 LM135/LM235/LM335, LM135A/LM235A/LM335A

*To calibrate adjust R2 for 2.554V across LM336. Adjust R1 for correct output. THERMOCOUPLE COLD JUNCTION COMPENSATION Compensation for Grounded Thermocouple 569806 *Select R3 for proper thermocouple type THERMO- R3 SEEBECK COUPLE (±1%) COEFFICIENT J 377Ω 52.3 μV/°C T 308Ω 42.8 μV/°C K 293Ω 40.8 μV/°C S 45.8Ω 6.4 μV/°C Adjustments: Compensates for both sensor and resistor tolerances 1. Short LM329B 2. Adjust R1 for Seebeck Coefficient times ambient temperature (in degrees K) across R3. 3. Short LM335 and adjust R2 for voltage across R3 corresponding to thermocouple type. J 14.32 mV K 11.17 mV T 11.79 mV S 1.768 mV 9 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A

Single Power Supply Cold Junction Compensation 569811 *Select R3 and R4 for thermocouple type THERMO- R3 R4 SEEBECK COUPLE COEFFICIENT J 1.05K 385Ω 52.3 μV/°C T 856Ω 315Ω 42.8 μV/°C K 816Ω 300Ω 40.8 μV/°C S 128Ω 46.3Ω 6.4 μV/°C Adjustments: 1. Adjust R1 for the voltage across R3 equal to the Seebeck Coefficient times ambient temperature in degrees Kelvin. 2. Adjust R2 for voltage across R4 corresponding to thermocouple. J 14.32 mV T 11.79 mV K 11.17 mV S 1.768 mV www.national.com 10 LM135/LM235/LM335, LM135A/LM235A/LM335A

Centigrade Calibrated Thermocouple Thermometer 569812 Terminate thermocouple reference junction in close proximity to LM335. Adjustments: 1. Apply signal in place of thermocouple and adjust R3 for a gain of 245.7. 2. Short non-inverting input of LM308A and output of LM329B to ground. 3. Adjust R1 so that VOUT = 2.982V @ 25°C. 4. Remove short across LM329B and adjust R2 so that VOUT = 246 mV @ 25°C. 5. Remove short across thermocouple. Fast Charger for Nickel-Cadmium Batteries 569813 †Adjust D1 to 50 mV greater VZ than D2. Charge terminates on 5°C temperature rise. Couple D2 to battery. Differential Temperature Sensor 569807 11 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A

Differential Temperature Sensor 569814 Variable Offset Thermometer‡ 569815 †Adjust for zero with sensor at 0°C and 10T pot set at 0°C *Adjust for zero output with 10T pot set at 100°C and sensor at 100°C ‡Output reads difference between temperature and dial setting of 10T pot www.national.com 12 LM135/LM235/LM335, LM135A/LM235A/LM335A

Ground Referred Centigrade Thermometer 569816 Air Flow Detector* 569817 *Self heating is used to detect air flow DEFINITION OF TERMS Operating Output Voltage: The voltage appearing across the positive and negative terminals of the device at specified conditions of operating temperature and current. Uncalibrated Temperature Error: The error between the operating output voltage at 10 mV/°K and case temperature at specified conditions of current and case temperature. Calibrated Temperature Error: The error between operating output voltage and case temperature at 10 mV/°K over a tem- perature range at a specified operating current with the 25°C error adjusted to zero. 13 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A

Physical Dimensions inches (millimeters) unless otherwise noted 8-Pin SOIC TO-92 www.national.com 14 LM135/LM235/LM335, LM135A/LM235A/LM335A

15 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A

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