FM50 — Analog Temperature Sensor Features Description As a precision CMOS temperature sensor, the FM50 is cost effective for accurate, low-power, temperaturemonitoring applications. Output voltage versus temperature is extremely linear. With no load, the supply current is typically 130µA. For normal operation, the load on VOUT should be 100KΩ or less. Analog Output: 10mV/°C Range: -40 to 125°C Range Accuracy: ±2°C at 25°C Supply Current: 170μA Maximum Output Drive: 25μA Self-heating: <0.1°C Operating Voltage: +2.4V to +6V Accuracy is typically ±0.5°C at room temperature, and better than ±2°C from 0 to 75°C. Applications In a typical application, a remotely mounted FM50 is monitored by a microcontroller with an analog A/D converter input. Alternatively, the FM50 can drive a comparator with a high-impedance input. Mobile Phones FM50 is available in a 3-pin SOT-23 package. Computers Battery Management Office Equipment HVAC Power Supply Modules Disk Drives Automotive Ordering Information Part Number Operating Temperature Range Package Packing Method FM50S3X -40 to +125°C 3-Pin SOT-23 3000 Units, Tape and Reel All packages are lead free per JEDEC: J-STD-020B standard. Figure 1. Output Voltage vs. Temperature © 2004 Fairchild Semiconductor Corporation FM50 • Rev. 1.1.1 www.fairchildsemi.com FM50 — Analog Temperature Sensor April 2008 FM50 — Analog Temperature Sensor Pin Configuration Figure 2. Pin Configuration Pin Definitions Pin # Name Type Description 1 VDD Power Power Supply. 2.4 to 6.0V. 2 VOUT Analog Output 3 GND Power © 2004 Fairchild Semiconductor Corporation FM50 • Rev. 1.1.1 Temperature Sensor. Analog output voltage indicating temperature. VOUT = 500+10T(°C) mV. Ground. www.fairchildsemi.com 2 Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. Symbol Parameter Min. Max. Unit VDD Supply Voltage +7 V VOUT Output Voltage VDD+0.5 V IOUT Output Current 10 µA Operating Temperature Range -50 +150 °C TSTG TJ Storage Temperature Range -60 +150 °C TL Lead Soldering Temperature +220 °C ESD Human Body Model, JESD22-A114 Machine Model, JESD22-A115 (1) 2000 (2) V 250 FM50 — Analog Temperature Sensor Absolute Maximum Ratings Notes: 1. Human body model: 100pF capacitor discharged through a t 1.5kW resister into each pin. 2. Machine model: 200pF capacitor discharged directly into each pin. Electrical Characteristics Limits apply for -40°C ≤ TA ≤ +125°C and VDD=+5.0V unless otherwise noted. These specifications are guaranteed only for the test conditions listed. Symbol Parameter Conditions Min. Typ. Max. Units Sensitivity 9.7 10.0 10.3 mV/°C Output at 25°C 740 750 760 mV TA=+25°C -2.0 ±0.5 +2.0 TA=-40°C (TMIN) -3.5 ±1.0 +3.5 -3 ±1 +3 Transfer Characteristics AOUT (3) Accuracy TA=+125°C (TMAX) TA Temperature Range °C -40 +125 °C Non-Linearity -0.8 +0.8 °C Output Voltage Range 100 1750 mV (4) Output VOUT IONSN IONSG IOL Output Current Source Sensing 25 mA Output Current Sink ROUT Output Resistance RLOAD Load Regulation µA Surge 50 100kΩ Load at 25°C 1 µA 10 kΩ mV/mA Power VDD IQ Supply Voltage Quiescent Current 2.4 No Output Load 6.0 V 170 µA Package ΘJA Thermal Resistance 260 °C/W Notes: 3. Accuracy (expressed in °C)= difference between calculated output voltage and measured output voltage. Calculated output voltage =10m/V°C multiplied by the device’s case temperature at specific conditions of temperature, voltage and power supply, added to 500mV. 4. Non-linearity is defined as the deviation of the output voltage vs. temperature curve from the best fit straight line over the rated temperature range. © 2004 Fairchild Semiconductor Corporation FM50 • Rev. 1.1.1 www.fairchildsemi.com 3 FM50 — Analog Temperature Sensor Typical Performance Characteristics Figure 3. Accuracy vs. Temperature Figure 4. Typical IDD vs. Temperature Figure 5. Typical Sensitivity to Supply Voltage © 2004 Fairchild Semiconductor Corporation FM50 • Rev. 1.1.1 www.fairchildsemi.com 4 The FM50 contains a thermal diode, calibration circuits, and amplifiers. Since the FM50 is calibrated at 33°C, the nominal output in mV is: thermal For measurement accuracy of the order of tenths of 1°C, adequate settling time must be allowed. For a typical circuit board installation, 15 minutes should be allowed to elapse after reading temperature within 1~2°C of the expected final value. Once VOUT has ceased to slew and is stable (with or without about ±0.1°C noise) for about five minutes, temperature can be calculated. (1) VOUT = 830 + 10 • (T-33) where T is the expressed in °C. Thermal Delay Errors junction temperature At 33°C, the tolerances are: Offset is ±3mV. Location Errors Slope is ±0.3mV/°C. These values accommodate the specified accuracies at -40, +25, and +125°C. Position is source of error. Even within a controlled thermal environment, changing location by a few inches can lead to errors of several tenths of 1°C. Output structure is an N-channel CMOS transistor driving a P-channel load. Available current is typically 50μA to ground. Series resistance is typically 7kΩ, charging and 2kΩ, discharging through a capacitor connected from VOUT to ground. Mounting The FM50 can be easily mounted by gluing or cementing it to a surface. In this case, its temperature will be within about 0.2°C of the temperature of the surface to which it is attached if the ambient air temperature is almost the same as the surface temperature. If the air temperature is much higher or lower than the surface temperature, the actual temperature of the die will be at an intermediate temperature between the surface temperature and the air temperature. Following application of power to VDD, VOUT is accurate after a delay of approximately 80ms. Application Information Although the FM50 is a simple device, care must be taken to ensure that temperature is measured accurately. The major sources of errors are: FM50 — Analog Temperature Sensor Functional Description To ensure good thermal conductivity, the backside of the die is directly attached to the GND pin. The lands and traces to the FM50 are part of the printed circuit board, for which the temperature is being measured. These printed circuit board lands and traces do not cause the FM50’s temperature to deviate from the desired temperature. Voltage Errors Thermal Delay Errors Location Errors Alternatively, the FM50 can be mounted inside a sealed-end metal tube and can be dipped into a bath or screwed into a threaded hole in a tank. As with any IC, the FM50 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 paint or dips, can be used to ensure that moisture cannot corrode the FM50 or it connections. Voltage Errors Figure 6. Recommended Electrical Connections A Kelvin connection is recommended to avoid errors due to voltage drops in the ground connections. Although the typical 130μA supply current draw only causes a 130μV error; if the series resistance is 1Ω, a 100mA current supply to adjacent circuits can cause a 10mV drop across 100mΩ (10mΩ is a typical value for soldered joints or contact resistance), leading to a 1°C error. For this reason, the FM50 should be Kelvin connected, as shown in Figure 6. © 2004 Fairchild Semiconductor Corporation FM50 • Rev. 1.1.1 www.fairchildsemi.com 5 FM50 — Analog Temperature Sensor Typical Application Circuits Figure 7. Serial Output Temperature to Digital Converter (Full Scale = +125°C) Figure 8. Parallel Output Temperature to Digital Converter (Full Scale = +125°C) Figure 9. Thermostat / Fan Controller © 2004 Fairchild Semiconductor Corporation FM50 • Rev. 1.1.1 www.fairchildsemi.com 6 FM50 — Analog Temperature Sensor Physical Dimensions Figure 10. 3-Pin SOT Package Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/ © 2004 Fairchild Semiconductor Corporation FM50 • Rev. 1.1.1 www.fairchildsemi.com 7 FM50 — Analog Temperature Sensor © 2004 Fairchild Semiconductor Corporation FM50 • Rev. 1.1.1 www.fairchildsemi.com 8