How to choose NTC thermistor temperature sensor

The thermistor of the negative temperature coefficient (NTC) is made of sintering metal oxides. They show that the sharp decline in resistance is proportional to the slightly rising temperature.

Their resistance is calculated by lowering the heat -allergic resistance and measured voltage generated by a small DC (DC).
application
● Temperature measurement
● Temperature compensation
● Temperature control

Five basic considerations of 5 basic considerations when selecting NTC thermistor
Temperature range

● When selecting the temperature sensor, the first thing to consider is the temperature range of the application.
● Because NTC thermistor is well performed well within the scope of working in -50 ° C to 250 ° C, they are very suitable for widespread application of many different industries.

Accuracy
● In the basic sensor type, the NTC thermistor is the ability to reach the highest accuracy within the range of -50 ° C to 150 ° C. For glass packaging thermistor is as high as 250 ° C.
● The accuracy range is 0.05 ° C to 1.00 ° C.

Stablize
● In applications with long -term operation, stability is important. The temperature sensor will drift over time, depending on their materials, structure and packaging.
● The NTC thermistor with epoxy resin is 0.2 ° C each year, while the sealed NTC thermistor is only 0.02 ° C each year.

Package
● Packaging requirements depend on the environment of the sensor.
● NTC thermistor can be customized and packaged in various cases according to the application requirements. They can also use epoxy resin coating or glass packaging to provide further protection.

Noise
● NTC thermistor has excellent resistance to electrical noise and lead resistance.

More precautions
NTC thermistor has specific electrical characteristics:
● Current time characteristics
● Voltage-current characteristics
● Resistance temperature characteristics

Product type and size
● Thermistor users usually know what other physical characteristics are needed in size, thermal response, time response, and thermistor configuration. Even if the data is lacking, it should be easy to reduce the range of NTC thermistor, but it must be carefully analyzed the expected application of thermistor.

Resistance temperature curve
● The Weilian data table contains a table or matrix of the resistance ratio and temperature relationship of each NTC thermistor product. It also provides coefficient α and β for specific equations to help users or designers convey the resistance of the resistance according to the temperature accuracy and calculate the temperature coefficient of each curve.
● The range of materials that can be used to manufacture thermal resistance is wide, but there are some restrictions based on the size, operation and storage temperature range and nominal resistance values.

Nominal resistance value
● The next factors to consider is whether the application needs curve matching or point matching. This will allow the nominal resistance value required at a given temperature.
Velian provides the nominal resistance value for its NTC thermistor. The standard reference temperature is 25 ° C, but buyers and designers can require different temperatures.
● Reminder: If you cannot obtain the required resistance in the combination of product types and material composition, you must determine which features are priority: product type/size, material preferences, or resistance ratio.

Resistance
● When viewing the product specification table, Vilian provides standard tolerance. For example, discs or chip -type thermistor usually have zero -power resistance distribution from ± 1% to ± 20%.
● In order to save costs, Victoria recommends the use of as much tolerance specifications as possible related to expected uses.

Types of thermistor of NTC
● Disc and chip: They have coats with or without naked copper or tin -plated copper leads. Applicable to
Thermal resistance of extensive resistance value in various situations.

● Epoxy resin: Epoxy resin is soaked and welded between the TEFLON/PVC wires with a cover. Their small size is easy to install, and they can match or curve matching.

● Glass packaging: It is a great choice when dealing with extreme environmental conditions and stability. Configuration includes
Radial leader or axial lead thermistor.

● probe component:
Provide various shells according to application requirements.

● Surface installation: The configuration options include the surround installation of bulk, roll band, double -sided and cash -band silver terminals. These thermal resistances are made of nickel potential, which works well in the precision circuit.

The calculation you may need
● α -constant (%/° C)
resistance temperature coefficient is the ratio of zero power resistance at the specified temperature T. The ratio of the zero power resistance of the thermistor and the zero -power resistance of the thermistor.

●β -constant (° K)
The constant of the material of the NTC thermistor is to measure the comparison of its resistance at a temperature at different temperatures. The reference temperature of the Velian thermistor used in the following formula is 298.15°K 和 348.15°K。

As shown above, you can use Beta to calculate the resistance of NTC thermistor under the given temperature, but there is another use Steinhart & Hart the equation is more accurate.

You can use the temperature range of the heating resistance of NTC with the Whist Tongqiao bridge.