HTM2500LF - Temperature and Relative Humidity Module * Hermetic Housing * Humidity calibrated within +/-2% @55%RH * Temperature measurement through NTC 10kOhms +/-1% direct output * Small size product * Typical 1 to 4 Volt DC output for 0 to 100%RH at 5Vdc DESCRIPTION Based on the rugged HTS2035SMD humidity / temperature sensor, HTM2500LF is a dedicated humidity and temperature transducer designed for OEM applications where a reliable and accurate measurement is needed. Direct interface with a micro-controller is made possible with the module's humidity linear voltage output. FEATURES * Full interchangeability * High reliability and long term stability * Not affected by water immersion * Ratiometric to voltage supply * Suitable for 3 to 10 Vdc supply voltage Humidity Sensor Specific Features * Instantaneous de-saturation after long periods in saturation phase * Fast response time * High resistance to chemicals * Patented solid polymer structure Temperature Sensor Specific Features * Stable * High sensitivity APPLICATIONS * * * * ... Industrial Process control Hygrostat Data logger HTM2500LF HPC169 Rev C www.meas-spec.com 1/9 October 2012 HTM2500LF - Temperature and Relative Humidity Module PERFORMANCE SPECS MAXIMUM RATINGS Ratings Storage Temperature Storage Humidity Supply Voltage (Peak) Humidity Operating Range Temperature Operating Range Symbol Tstg RHstg Vs RH Ta Value -40 to 85 0 to 100 12 0 to 100 -40 to 85 Unit C % RH Vdc % RH C Peak conditions: less than 10% of the operating time ELECTRICAL CHARACTERISTICS (Ta=23C, Vs=5Vdc +/-5%, R L>1M unless otherwise stated) Humidity Characteristics Humidity Measuring Range Relative Humidity Accuracy (10 to 95% RH) Supply Voltage Nominal Output @55%RH (at 5Vdc) Current consumption Temperature Coefficient (10 to 50C) Average Sensitivity from 33% to 75%RH Sink Current Capability (RL=15k) Recovery time after 150 hours of condensation Humidity Hysteresis Long term stability (1) Time Constant (at 63% of signal, static) 33% to 76%RH Output Impedance (1) Symbol RH RH Vs Vout Ic Tcc Vout/RH Is tr Min 1 4.75 2.42 Typ +/-3 5.00 2.48 1.0 +0.1 +26 Max 99 +/-5 5.25 2.54 1.2 Unit %RH %RH Vdc V mA %RH/C mV/%RH A s %RH %RH/yr s 300 10 +/-1.5 +/-0.5 5 70 T Z At 1m/s air flow (Ta=25C) Temperature Characteristics Nominal Resistance @25C Beta value: B25/50 Temperature Measuring Range* Nominal Resistance Tolerance @25C Beta Value Tolerance Response Time Symbol R Ta RN Min 3347 -40 Typ 10 3380 Max Unit k K C % % s 3413 85 1 1 10 * For temperature upper than 60C, specific high te mperature cable is required: HTM2500LFL products HTM2500LF HPC169 Rev C www.meas-spec.com 2/9 October 2012 HTM2500LF - Temperature and Relative Humidity Module TYPICAL PERFORMANCE CURVES HUMIDITY SENSOR * Typical response look-up table (Vs = 5V) RH (%) 10 15 20 25 30 35 40 45 50 * Vout (mV) 1235 1390 1540 1685 1825 1960 2090 2220 2350 RH (%) 55 60 65 70 75 80 85 90 95 Vout (mV) 2480 2605 2730 2860 2990 3125 3260 3405 3555 Modeled linear voltage output (Vs = 5V) 4000 100 Relative Humidity (%RH) Output Voltage (mV) 90 3500 3000 2500 2000 1500 80 70 60 50 40 30 20 10 1000 0 0 10 20 30 40 50 60 70 80 90 100 1000 1500 Relative Humidity (%RH) * 2000 2500 3000 3500 4000 Output Voltage (mV) Linear Equations Vout = 26.65 * RH + 1006 RH = 0.0375 * Vout - 37.7 with Vout in mV and RH in % * Polynomial Equations -3 3 -1 2 Vout = 1.05E * RH - 1.76E * RH + 35.2 * RH + 898.6 -9 3 -5 2 -3 RH = -1.92E * Vout + 1.44E * Vout + 3.4E * Vout - 12.4 with Vout in mV and RH in % * Measurement Conditions HTM2500LF is specified for accurate measurements within 10 to 95% RH. Excursion out of this range (<10% or >95% RH, including condensation) does not affect the reliability of HTM2500LF characteristics. HTM2500LF HPC169 Rev C www.meas-spec.com 3/9 October 2012 HTM2500LF - Temperature and Relative Humidity Module * Error Budget at 23C HTM2500LF Error Limits: Temperature coefficient compensation: RH Cor ( % = RH read % x 1 - (T a - 23)x 2.4 E -3 ) HTM2500LF Linearity Error: Non-linearity and temperature compensation: 2 - 1.9206 E -9 V out + 1.437 E -5 Vout + 3.421 E -3 V - 12.4 out RH % = 1 + (T a - 23) x 2.4 E -3 3 with Vout in mV, RH in % and Ta in C HTM2500LF HPC169 Rev C www.meas-spec.com 4/9 October 2012 HTM2500LF - Temperature and Relative Humidity Module HTM2500LF TEMPERATURE SENSOR: DIRECT NTC OUTPUT * Typical temperature output Depending on the needed temperature measurement range and associated accuracy, we suggest two methods to access to the NTC resistance values. RT = RN x e RT RN T, TN e 1 1 T TN - NTC resistance in at temperature T in K NTC resistance in at rated temperature T in K Temperature in K Beta value, material specific constant of NTC Base of natural logarithm (e=2.71828) The exponential relation only roughly describes the actual characteristic of an NTC thermistor can, however, the material parameter in reality also depend on temperature. So this approach is suitable for describing a restricted range around the rated temperature or resistance with sufficient accuracy. For practical applications, a more precise description of the real R/T curve may be required. Either more complicated approaches (e.g. the Steinhart-Hart equation) are used or the resistance/temperature relation as given in tabulation form. The below table has been experimentally determined with utmost accuracy for temperature increments of 1 degree. Actual values may also be influenced by inherent self-heating properties of NTCs. Please refer to MEAS-France Application Note HPC106 "Low power NTC measurement". * Temperature look-up table Temp (C) -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 HTM2500LF HPC169 Rev C R () 195652 148171 113347 87559 68237 53650 42506 33892 27219 22021 17926 14674 12081 Temp (C) 25 30 35 40 45 50 55 60 65 70 75 80 85 www.meas-spec.com 5/9 R () 10000 8315 6948 5834 4917 4161 3535 3014 2586 2228 1925 1669 1452 October 2012 HTM2500LF - Temperature and Relative Humidity Module * Steinhart-Hart coefficients According to the equation below, the Steinhart-Hart coefficients for the operating temperature range for HTM2500LF thermistor are: 1 = a + b * ln( R ) + C * ln( R) * ln( R ) * ln( R) T NTC resistance in at temperature T in K Temperature in K Constant value (a = 8.54942E-04) Constant value (b = 2.57305E-04) Constant value (c = 1.65368E-07) R T a b c * Temperature Interface Circuit Concerning the temperature sensor of the HTM2500LF, the following measuring method described below is based on a voltage bridge divider circuit. It uses only one resistor component (Rbatch) at 1% to design HTM2500LF temperature sensor interfacing circuit. Rbatch is chosen to be equal to NTC @25C to get: V out = Vcc/2 @25C. The proposal method connects Rbatch to Vcc (5Vdc) and NTC to Ground. It leads to a negative slope characteristic (Pull-Up Configuration). VOUT (mV ) = W2 VCC Temp (C) R ( ) -40 -30 -20 -10 0 10 20 25 30 40 50 60 70 80 195652 113347 68237 42506 27219 17926 12081 10000 8315 5834 4161 3014 2228 1669 Rbatch 10k W4 NTC Resistance output HTM2500LF NTC 10k @25C Vout (mV) W1 Ground HTM2500LF HPC169 Rev C Vcc(mV ) * NTC HTM 2500LF () Rbatch () + NTC HTM 2500LF () www.meas-spec.com 6/9 Pull-up Configuration Vout (mV) 4757 4595 4361 4048 3657 3210 2736 2500 2270 1842 1469 1158 911 715 October 2012 HTM2500LF - Temperature and Relative Humidity Module SUGGESTED APPLICATION Steps of 1% RH are achievable by using 8-bit A/D. If more resolution is required, a 10bit A/D needs to be used and a third display will be added, giving steps of 0.2% RH. QUALIFICATION PROCESS RESISTANCE TO PHYSICAL AND CHEMICAL STRESSES * * * HTM2500LF has passed through qualification processes of MEAS-France including vibration, shock, storage, high temperature and humidity, ESD. Additional tests under harsh chemical conditions demonstrate good operation in presence of salt atmosphere, SO2 (0.5%, H2S (0.5%), 03, NOx, NO, CO, CO2, Softener, Soap, Toluene, acids (H2SO4, HNO3, HCI), HMDS, Insecticide, Cigarette smoke, this is not an exhaustive list. HTM2500LF is not light sensitive. SPECIFIC PRECAUTIONS * * HTM2500LF is not protected against reversed polarity - Check carefully when connecting the device. If you wish to use HTM2500LF in a chemical atmosphere not listed above, consult us. HTM2500LF HPC169 Rev C www.meas-spec.com 7/9 October 2012 HTM2500LF - Temperature and Relative Humidity Module PACKAGE OUTLINE Dim Min (mm) Max (mm) A 53 55 B 74.3 76.3 C 11.2 11.6 200 250 1450 1550 D* (HTM2500LF) D* (HTM2500LFL) *Specific length available on request For operating temperature upper than 60C, specific high temperature cable is required (1500mm long) Wire Cable Color HTM2500LF Cable Color HTM2500LFL W1 Brown Black W2 White Orange Supply Voltage W3 Yellow Yellow Humidity Voltage Output W4 Green Purple Temperature Output (NTC Direct) W5 Black (thick) Black (thick) Function Ground Shield HTM2500LF weight: 17.5g HTM2500LFL weight: 50g HTM2500LF wire characteristics: AWG 24 for W1, W2, W3 and W4 / AWG 16 for W5 HTM2500LFL wire characteristics: AWG 24 for W1, W2, W3 and W4 / AWG 16 for W5 HTM2500LF HPC169 Rev C www.meas-spec.com 8/9 October 2012 HTM2500LF - Temperature and Relative Humidity Module ORDERING INFORMATION HPP809A031 : HTM2500LF HUMIDITY VOLTAGE OUTPUT + NTC (TEMPERATURE DIRECT OUTPUT) HPP809A033 : HTM2500LFL HUMIDITY VOLTAGE OUTPUT + NTC (TEMPERATURE DIRECT OUTPUT) WITH LONG CABLE (MULTIPLE PACKAGE QUANTITY OF 10 PIECES) Customer Service contact details Measurement Specialties, Inc - MEAS France Impasse Jeanne Benozzi CS 83 163 31027 Toulouse Cedex 3 FRANCE Tel: +33 (0)5 820 822 02 Fax: +33(0)5 820 821 51 Sales: humidity.sales@meas-spec.com Revision 0 A B C Comments Document creation Temperature operating range updated, HTM25X0LFL references added New MEAS template, Temperature operating range updated, RH polynomial equation modified, package outline paragraph updated New combined RH/Temp sensor implemented, HTM2530LF product reference deleted Who D. LE GALL Date July 09 D. LE GALL December 09 D. LE GALL January 12 D. LE GALL October 12 The information in this sheet has been carefully reviewed and is believed to be accurate; however, no responsibility is assumed for inaccuracies. Furthermore, this information does not convey to the purchaser of such devices any license under the patent rights to the manufacturer. Measurement Specialties, Inc. reserves the right to make changes without further notice to any product herein. Measurement Specialties, Inc. makes no warranty, representation or guarantee regarding the suitability of its product for any particular purpose, nor does Measurement Specialties, Inc. assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability, including without limitation consequential or incidental damages. Typical parameters can and do vary in different applications. All operating parameters must be validated for each customer application by customer's technical experts. Measurement Specialties, Inc. does not convey any license under its patent rights nor the rights of others. HTM2500LF HPC169 Rev C www.meas-spec.com 9/9 October 2012