LM62 LM6 2 2.7V, 15.6 mV/C SOT-23 Temperature Sensor Literature Number: SNIS105D LM62 2.7V, 15.6 mV/C SOT-23 Temperature Sensor General Description Features The LM62 is a precision integrated-circuit temperature sensor that can sense a 0C to +90C temperature range while operating from a single +3.0V supply. The LM62's output voltage is linearly proportional to Celsius (Centigrade) temperature (+15.6 mV/C) and has a DC offset of +480 mV. The offset allows reading temperatures down to 0C without the need for a negative supply. The nominal output voltage of the LM62 ranges from +480 mV to +1884 mV for a 0C to +90C temperature range. The LM62 is calibrated to provide accuracies of 2.0C at room temperature and +2.5C/-2.0C over the full 0C to +90C temperature range. The LM62's linear output, +480 mV offset, and factory calibration simplify external circuitry required in a single supply environment where reading temperatures down to 0C is required. Because the LM62's quiescent current is less than 130 A, self-heating is limited to a very low 0.2C in still air. Shutdown capability for the LM62 is intrinsic because its inherent low power consumption allows it to be powered directly from the output of many logic gates. Calibrated linear scale factor of +15.6 mV/C Rated for full 0C to +90C range with 3.0V supply Suitable for remote applications Applications Cellular Phones Computers Power Supply Modules Battery Management FAX Machines Printers HVAC Disk Drives Appliances Key Specifications Accuracy at 25C Temperature Slope Power Supply Voltage Range Current Drain @ 25C Nonlinearity Output Impedance 2.0 or 3.0C (max) +15.6 mV/C +2.7V to +10V 130 A (max) 0.8C (max) 4.7 k (max) Typical Application Connection Diagram SOT-23 10089301 Top View See NS Package Number mf03a 10089302 VO = (+15.6 mV/C x TC) + 480 mV Ordering Information Order Number LM62BIM3 Device Top Mark Supplied As T7B 1000 Units, Tape and Reel LM62BIM3X T7B 3000 Units, Tape and Reel LM62CIM3 T7C 1000 Units, Tape and Reel LM62CIM3X T7C 3000 Units, Tape and Reel (c) 2010 National Semiconductor Corporation 100893 Temperature (T) Typical VO +90C +1884 mV +70C +1572 mV +25C 870 mV 0C +480 mV FIGURE 1. Full-Range Centigrade Temperature Sensor (0C to +90C) Stabilizing a Crystal Oscillator www.national.com LM62 2.7V, 15.6 mV/C, SOT-23 Temperature Sensor February 8, 2010 LM62 Human Body Model Machine Model Absolute Maximum Ratings (Note 1) Supply Voltage Output Voltage Output Current Input Current at any pin (Note 2) Storage Temperature Junction Temperature, max (TJMAX) ESD Susceptibility (Note 3) : +12V to -0.2V (+VS + 0.6V) to -0.6V 10 mA 5 mA -65C to +150C 2500V 250V Operating Ratings (Note 1) TMIN TA TMAX Specified Temperature Range: 0C TA +90C LM62B, LM62C Supply Voltage Range (+VS) +2.7V to +10V Thermal Resistance, JA(Note 5) +125C 450C/W Soldering process must comply with National Semiconductor's Reflow Temperature Profile specifications. Refer to www.national.com/packaging. (Note 4) Electrical Characteristics Unless otherwise noted, these specifications apply for +VS = +3.0 VDC. Boldface limits apply for TA = TJ = TMIN to TMAX ; all other limits TA = TJ = 25C. Parameter Conditions Typical (Note 6) Accuracy (Note 8) Change of Quiescent Current Units (Limit) 3.0 C (max) +4.0/-3.0 C (max) 0.8 1.0 C (max) +16.1 +15.1 +16.3 +14.9 mV/C (max) mV/C (min) +3.0V +VS +10V 4.7 4.7 k (max) 0C TA +75C, +VS= +2.7V 4.4 4.4 +3.0V +VS +10V 1.13 1.13 mV/V (max) +2.7V +VS +3.3V, 0C TA +75C 9.7 9.7 mV (max) 130 130 A (max) 165 165 A (max) +480 Sensor Gain (Average Slope) Quiescent Current Limits (Note 7) 2.0 Nonlinearity (Note 9) Line Regulation (Note 10) LM62C Limits (Note 7) +2.5/-2.0 Output Voltage at 0C Output Impedance LM62B +16 +2.7V +VS +10V 82 +2.7V +VS +10V Temperature Coefficient of mV k (max) 5 A 0.2 A/C 0.2 C Quiescent Current Long Term Stability (Note 11) TJ=TMAX=+100C, for 1000 hours Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. Note 2: When the input voltage (VI) at any pin exceeds power supplies (VI < GND or VI > +VS), the current at that pin should be limited to 5 mA. Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 k resistor into each pin. The machine model is a 200 pF capacitor discharged directly into each pin. Note 4: Reflow temperature profiles are different for lead-free and non-lead-free packages. Note 5: The junction to ambient thermal resistance (JA) is specified without a heat sink in still air. Note 6: Typicals are at TJ = TA = 25C and represent most likely parametric norm. Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level). Note 8: Accuracy is defined as the error between the output voltage and +15.6 mV/C times the device's case temperature plus 480 mV, at specified conditions of voltage, current, and temperature (expressed in C). Note 9: 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 10: 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 11: For best long-term stability, any precision circuit will give best results if the unit is aged at a warm temperature, and/or temperature cycled for at least 46 hours before long-term life test begins. This is especially true when a small (Surface-Mount) part is wave-soldered; allow time for stress relaxation to occur. The majority of the drift will occur in the first 1000 hours at elevated temperatures. The drift after 1000 hours will not continue at the first 1000 hour rate. www.national.com 2 To generate these curves the LM62 was mounted to a printed circuit board as shown in Figure 2. Thermal Resistance Junction to Air Thermal Time Constant 10089304 10089303 Thermal Response in Still Air with Heat Sink Thermal Response in Stirred Oil Bath with Heat Sink 10089305 10089306 Thermal Response in Still Air without a Heat Sink Quiescent Current vs. Temperature 10089309 10089308 3 www.national.com LM62 Typical Performance Characteristics LM62 Accuracy vs Temperature Noise Voltage 10089310 10089311 Supply Voltage vs Supply Current Start-Up Response 10089322 10089312 Circuit Board 10089314 FIGURE 2. Printed Circuit Board Used for Heat Sink to Generate All Curves. 1/2 Square Printed Circuit Board with 2 oz. Copper Foil or Similar. www.national.com 4 Note 12: Heat sink used is 1/2 square printed circuit board with 2 oz. foil with part attached as shown in Figure 2 . The LM62 can be applied easily in the same way as other integrated-circuit temperature sensors. It can be glued or cemented to a surface. The temperature that the LM62 is sensing will be within about +0.2C of the surface temperature that LM62's leads are attached to. 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 measured would be at an intermediate temperature between the surface temperature and the air temperature. To ensure good thermal conductivity the backside of the LM62 die is directly attached to the GND pin. The lands and traces to the LM62 will, of course, be part of the printed circuit board, which is the object whose temperature is being measured. These printed circuit board lands and traces will not cause the LM62's temperature to deviate from the desired temperature. Alternatively, the LM62 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 LM62 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 ensure that moisture cannot corrode the LM62 or its connections. The thermal resistance junction to ambient (JA) is the parameter used to calculate the rise of a device junction temperature due to its power dissipation. For the LM62 the equation used to calculate the rise in the die temperature is as follows: TJ = TA + JA [(+VS IQ) + (+VS - VO) IL] where IQ is the quiescent current and ILis the load current on the output. Since the LM62's junction temperature is the actual temperature being measured care should be taken to minimize the load current that the LM62 is required to drive. The table shown in Figure 3 summarizes the rise in die temperature of the LM62 without any loading, and the thermal resistance for different conditions. Note 13: Part soldered to 30 gauge wire. SOT-23 no heat sink (Note 13) JA Still air Moving air FIGURE 3. Temperature Rise of LM62 Due to Self-Heating and Thermal Resistance (JA) 2.0 Capacitive Loads The LM62 handles capacitive loading well. Without any special precautions, the LM62 can drive any capacitive load as shown in Figure 4. Over the specified temperature range the LM62 has a maximum output impedance of 4.7 k. In an extremely noisy environment it may be necessary to add some filtering to minimize noise pickup. It is recommended that 0.1 F be added from +VS to GND to bypass the power supply voltage, as shown in Figure 5. In a noisy environment it may be necessary to add a capacitor from the output to ground. A 1 F output capacitor with the 4.7 k maximum output impedance will form a 34 Hz lowpass filter. Since the thermal time constant of the LM62 is much slower than the 30 ms time constant formed by the RC, the overall response time of the LM62 will not be significantly affected. For much larger capacitors this additional time lag will increase the overall response time of the LM62. 10089315 FIGURE 4. LM62 No Decoupling Required for Capacitive Load 10089316 SOT-23 small heat fin (Note 12) TJ - TA JA TJ - TA (C/W) (C) (C/W) (C) 450 0.17 260 0.1 180 0.07 FIGURE 5. LM62 with Filter for Noisy Environment 5 www.national.com LM62 1.0 Mounting LM62 10089317 FIGURE 6. Simplified Schematic 3.0 Applications Circuits 10089318 FIGURE 7. Centigrade Thermostat 10089319 FIGURE 8. Conserving Power Dissipation with Shutdown www.national.com 6 LM62 Physical Dimensions inches (millimeters) unless otherwise noted SOT-23 Molded Small Outline Transistor Package (M3) Order Number LM62BIM3 or LM62CIM3 NS Package Number mf03a 7 www.national.com LM62 2.7V, 15.6 mV/C, SOT-23 Temperature Sensor Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Design Support Amplifiers www.national.com/amplifiers WEBENCH(R) Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise(R) Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagicTM www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise(R) Design University THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION ("NATIONAL") PRODUCTS. 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