3DE502K

NTC Thermistors - Disc and Chip Style Temperature Measurement and Control Thermistors DISC and CHIP Style DISC & CHIP NTC STYLE NTC THERMISTOR Features • Wide Ohmic Value Range • Accurate & Stable • Fast Thermal Response Time • Tight Tolerances • High Sensitivity NTC Thermistors Negative Temperature Coefficient (NTC) thermistors are thermally sensitive semiconductor resistors which exhibit a decrease in resistance as absolute temperature increases. Change in the resistance of NTC thermistor can be brought about either by a change in the ambient temperature or internally by self-heating resulting from current flowing through the device. Most of the practical applications of NTC thermistors are based on these material characteristics. NTC Disc and Chip Style Devices Ametherm manufactures Disc and Chip style thermistors in resistance values ranging from 1.0 ohm to 500,000 ohms. These devices are suitable for a range of resistance values and temperature coefficients from relatively low resistance and temperature coefficients to very high values. Precision resistance tolerances are available to 1%. Standard resistance tolerances are from 5% to 20%. All tolerances are specified at 25°C or may be specified at any temperature within the operating temperature range of the thermistor. Thermistor Terminology for Temperature Measurement & Control Devices • • • The dissipation constant (D.C.) is the ratio, normally expressed in milliwatts per degree C (mw/°C), at a specified ambient temperature, of a change in power dissipated in a thermistor to the resultant change in body temperature. The thermal time constant (T.C.) is the time required for a thermistor to change 63.2% of the total difference between its initial and final body temperature when subjected to a step function change in temperature under zero-power conditions and is normally expressed in seconds (S). Alpha ( ) or Temperature Coefficient or Resistance is the temperature coefficient of resistance is the ratio at a specified temperature, T, of the rate of change of zeropower resistance with temperature to the zero-power resistance of the thermistor. The temperature coefficient is commonly expressed in percent per degree C (%/°C). NTC DISC & CHIP Selection Considerations • Select Req'd. Resistance Value & Temperature Coefficient • • • • Determine Accuracy Req'd. Review Power Dissipation Determine Operating Temperature Range Review Thermal Time Constant Thermistor Applications Time and temperature are two of the most frequently measured variables. There are numerous ways of the measuring temperature electronically, most commonly by thermocouples and negative temperature coefficient (NTC) thermistors. For general purpose temperature measurement, NTC temperature sensors can operate over a wide temperature range (-55 to +300°C). They are stable throughout a long lifetime, and are small and comparatively inexpensive. Typically, they have negative temperature coefficients between -3.3 and -4.9%/°C at 25°C. This is more than ten (10) times the sensitivity of a platinum resistance thermometer of the same nominal resistance. Ametherm's Disc & Chip style thermistors are used in many applications that require a high degree of accuracy and reliability. Some of the most popular applications of NTC thermistors include: • • • • Temperature Compensation Temperature Measurement & Control Fan Motor Control Fluid Level & Temperature Sensors NTC DISC & CHIP - Selection Process • • • • • Select R Value Determine R @ T Calculate DEV for R @ T Evaluate Power Rating (D.C.) Review T.C. Requirements Selection considerations for NTC Disc and Chip Devices Power dissipation is a common problem in the use of thermistors as they can only dissipate a certain amount of power. • If the power dissipated exceeds the dissipation constant (D.C.) rating of the sensor it is likely that it will exhibit self heating. 1DA101K-EC 100 A 0.1 0.06 3 10 28 0.07 1DA131J 130 A 0.1 0.06 3 10 28 0.07 1DA131K 130 A 0.1 0.06 3 10 28 0.07 1DA500J 50 A 0.1 0.03 3 6 28 0.07 1DA500K 50 A 0.1 0.03 3 6 28 0.07 1DB102J 1,000 B 0.1 0.06 3 10 28 0.07 1DB102K 1,000 B 0.1 0.06 3 10 28 0.07 1DB102K-EC 1,000 B 0.1 0.06 3 10 28 0.07 1DB501K 500 B 0.1 0.03 3 6 28 0.07 1DC103J 10,000 C 0.1 0.03 3 6 28 0.07 1DC103J-EC 10,000 C 0.1 0.08 4 12 28 0.07 1DC302J 3,000 C 0.1 0.08 4 12 28 0.07 1DC502J 5,000 C 0.1 0.08 4 12 28 0.07 1DC502J-EC 5,000 C 0.1 0.08 4 12 28 0.07 1DE104J 100,000 E 0.1 0.95 3 9 28 0.07 1DE104K 100,000 E 0.1 0.95 3 9 28 0.07 1DE104K-EC 10,000 E 0.1 0.95 3 9 28 0.07 2DA200J 20 A 0.2 0.05 7 20 24 0.1 2DA200K 20 A 0.2 0.05 7 20 24 0.1 2DA503J 50,000 A 0.2 0.05 7 20 24 0.1 2DB101K 100 B 0.2 0.025 7 18 24 0.1 2DB102J 1,000 B 0.2 0.025 7 18 24 0.1 2DB102J-EC 1,000 B 0.2 0.025 7 18 24 0.1 2DB102K 1,000 B 0.2 0.025 7 18 24 0.1 2DB151J 150 B 0.2 0.025 7 18 24 0.1 2DB151K 150 B 0.2 0.035 7 19 24 0.1 2DC102K 1,000 C 0.2 0.035 7 18 24 0.1 2DC302J 3,000 C 0.2 0.1 7 30 24 0.1 2DC302K 3,000 C 0.2 0.1 7 30 24 0.1 2DE103J 1,0000 E 0.2 0.04 7 17 24 0.1 2DE103K 1,0000 E 0.2 0.04 7 17 24 0.1 2DE503K 5,0000 E 0.2 0.04 7 17 24 0.1 3DA100J 10 A 0.3 0.06 8 48 24 0.1 3DA100K 10 A 0.3 0.06 8 48 24 0.1 3DB500J 50 B 0.3 0.025 8 35 24 0.1 3DB500K 50 B 0.3 0.025 8 35 24 0.1 3DE502J 5,000 E 0.3 0.025 8 35 24 0.1 3DE502K 5,000 E 0.3 0.025 8 35 24 0.1 © 1998 -2013 Ametherm, Inc