LM135A

LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors December 17, 2008 LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors General Description The LM135 series are precision, easily-calibrated, integrated circuit temperature sensors. Operating as a 2-terminal zener, the LM135 has a breakdown voltage directly proportional to absolute temperature at +10 mV/°K. With less than 1Ω dynamic impedance the device operates over a current range of 400 μA to 5 mA with virtually no change in performance. When calibrated at 25°C the LM135 has typically less than 1° C error over a 100°C temperature range. Unlike other sensors the LM135 has a linear output. Applications for the LM135 include almost any type of temperature sensing over a −55°C to 150°C temperature range. The low impedance and linear output make interfacing to readout or control circuitry especially easy. The LM135 operates over a −55°C to 150°C temperature range while the LM235 operates over a −40°C to 125°C temperature range. The LM335 operates from −40°C to 100°C. The LM135/LM235/LM335 are available packaged in hermetic TO-46 transistor packages while the LM335 is also available in plastic TO-92 packages. 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 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 Forward Current Storage Temperature 8-Pin SOIC Package TO-92 Package TO-46 Package 15 mA 10 mA −65°C to 150°C −60°C to 150°C −60°C to 180°C Specified Operating Temp. Range Continuous LM135, LM135A −55°C to 150°C LM235, LM235A −40°C to 125°C LM335, LM335A −40°C to 100°C Lead Temp. (Soldering, 10 seconds) 8-Pin SOIC Package: Vapor Phase (60 seconds): Infrared (15 seconds): TO-92 Package: TO-46 Package: Intermittent (Note 2) 150°C to 200°C 125°C to 150°C 100°C to 125°C 300°C 215°C 220°C 260°C 300°C Temperature Accuracy LM135/LM235, LM135A/LM235A Parameter Operating Output Voltage Uncalibrated Temperature Error Uncalibrated Temperature Error Temperature Error with 25°C Calibration Calibrated Error at Extended Temperatures Non-Linearity (Note 1) Conditions LM135A/LM235A Min Typ 2.98 0.5 1.3 0.3 2 0.3 0.5 Max 2.99 1 2.7 1 2.97 LM135/LM235 Min 2.95 Typ 2.98 1 2 0.5 2 0.3 1 Max 3.01 3 5 1.5 V °C °C °C °C °C Units TC = 25°C, IR = 1 mA TC = 25°C, IR = 1 mA TMIN ≤ TC ≤ TMAX, IR = 1 mA TMIN ≤ TC ≤ TMAX, IR = 1 mA TC = TMAX (Intermittent) IR = 1 mA (Note 1) Conditions Temperature Accuracy LM335, LM335A Parameter Operating Output Voltage Uncalibrated Temperature Error Uncalibrated Temperature Error Temperature Error with 25°C Calibration Calibrated Error at Extended Temperatures Non-Linearity LM335A Min Typ 2.98 1 2 0.5 2 0.3 1.5 Max 3.01 3 5 1 Min 2.92 2.95 LM335 Typ 2.98 2 4 1 2 0.3 1.5 Max 3.04 6 9 2 Units V °C °C °C °C °C TC = 25°C, IR = 1 mA TC = 25°C, IR = 1 mA TMIN ≤ TC ≤ TMAX, IR = 1 mA TMIN ≤ TC ≤ TMAX, IR = 1 mA TC = TMAX (Intermittent) IR = 1 mA (Note 1) Electrical Characteristics Parameter Operating Output Voltage Change with Current Dynamic Impedance Output Voltage Temperature Coefficient Time Constant Conditions 400 μA ≤ IR ≤ 5 mA At Constant Temperature IR = 1 mA LM135/LM235 LM135A/LM235A Min Typ 2.5 0.5 +10 Max 10 Min LM335 LM335A Typ 3 0.6 +10 80 10 1 0.2 Max 14 Units mV Ω mV/°C sec sec sec °C/khr Still Air 100 ft/Min Air Stirred Oil TC = 125°C 2 80 10 1 0.2 Time Stability www.national.com 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  θJA (Junction to Ambient)  θJC (Junction to Case) Note 4: Refer to RETS135H for military specifications. 8-Pin SOIC 165°C/W N/A TO-92 202°C/W 170°C/W TO-46 400°C/W N/A Connection Diagrams 8-Pin SOIC Surface Mount Package TO-92 Plastic Package TO-46 Metal Can Package* 569808 Bottom View 569825 569826 Top View *Case is connected to negative pin Bottom View Ordering Information Package Part Number LM335AM 8-Pin SOIC LM335AMX LM335M LM335MX TO-92 LM335AZ LM335Z LM135AH LM135H TO-46 LM235AH LM235H LM335AH LM335H Package Marking LM335AM LM335M LM335AZ LM335Z LM135AH LM135H LM235AH LM235H LM335AH LM335H Transport Media 95 Units/Rail 2.5k Units Tape and Reel 95 Units/Rail 2.5k Units Tape and Reel 1800 Bag 1800 Bag 1000 Bag 1000 Bag 1000 Bag 1000 Bag 1000 Bag 1000 Bag H03H Z03Z M08A NSC Drawing 3 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A Typical Performance Characteristics Reverse Voltage Change Calibrated Error 569827 569828 Reverse Characteristics Response Time 569829 569830 Dynamic Impedance Noise Voltage 569831 569832 www.national.com 4 LM135/LM235/LM335, LM135A/LM235A/LM335A Thermal Resistance Junction to Air Thermal Time Constant 569833 569834 Thermal Response in Still Air Thermal Response in Stirred Oil Bath 569835 569836 Forward Characteristics 569837 5 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A Application Information CALIBRATING THE LM135 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 extrapolated 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: Calibrated Sensor 569809 *Calibrate for 2.982V at 25°C Wide Operating Supply where T is the unknown temperature and To 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 resistance 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 proportional to absolute temperature the same as scale factor errors. WATERPROOFING SENSORS Meltable inner core heat shrinkable tubing such as manufactured 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. 569810 Minimum Temperature Sensing 569804 Average Temperature Sensing Typical Applications Basic Temperature Sensor 569818 569802 www.national.com 6 LM135/LM235/LM335, LM135A/LM235A/LM335A Remote Temperature Sensing AWG 14 16 18 20 22 24 IR = 1 mA FEET 4000 2500 1600 1000 IR = 0.5 mA* FEET 8000 5000 3200 2000 1250  625  400  800 *For IR = 0.5 mA, the trim pot must be deleted. 569819 Wire length for 1°C error due to wire drop 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 Fahrenheit Thermometer 569824 *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 THERMOCOUPLE J T K S R3 (±1%) 377Ω 308Ω 293Ω 45.8Ω SEEBECK COEFFICIENT 52.3 μV/°C 42.8 μV/°C 40.8 μV/°C  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 THERMOCOUPLE J T K S R3 1.05K 856Ω 816Ω 128Ω R4 385Ω 315Ω 300Ω 46.3Ω SEEBECK COEFFICIENT 52.3 μV/°C 42.8 μV/°C 40.8 μV/°C  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 temperature 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 NS Package Number M08A TO-92 NS Package Z03A www.national.com 14 LM135/LM235/LM335, LM135A/LM235A/LM335A TO-46 NS Package Number H03H 15 www.national.com LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers Audio Clock and Timing Data Converters Interface LVDS Power Management Switching Regulators LDOs LED Lighting Voltage Reference PowerWise® Solutions Serial Digital Interface (SDI) Temperature Sensors Wireless (PLL/VCO) www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/vref www.national.com/powerwise www.national.com/sdi www.national.com/tempsensors www.national.com/wireless WEBENCH® Tools App Notes Reference Designs Samples Eval Boards Packaging Green Compliance Distributors Design Support www.national.com/webench www.national.com/appnotes www.national.com/refdesigns www.national.com/samples www.national.com/evalboards www.national.com/packaging www.national.com/quality/green www.national.com/contacts www.national.com/quality www.national.com/feedback www.national.com/easy www.national.com/solutions www.national.com/milaero www.national.com/solarmagic www.national.com/AU Quality and Reliability Feedback/Support Design Made Easy Solutions Mil/Aero Solar Magic® Analog University® THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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