Continued from last article.
It needs to be noted that the δ value is the parameter of NTC thermistor before the secondary encapsulation by most of the manufacturers. Although the current determined by this parameter won’t produce self-thermal, but it affects the selection range of the parameter value. That’s because the max. non self-thermal power is increased after secondary encapsulation. The way to determine the current range by dissipation factor is to determine the accuracy of NTC thermistor first, and then the self-thermal power consumption allowed. For example, when the accuracy of NTC thermistor is 0.1°C, then the self-thermal temperature doesn’t exceed 0.1°C, that is to say, less than 0.1δ power won’t produce self-thermal power.
Other factors needed to be noted: 1. τa will be increased after secondary encapsulation. 2. It needs to pay attention to the medium of the parameter since δ and τa vary widely for the same one NTC thermistor in different media. 3. In flow air, it doesn’t influence the accuracy much that NTC thermistor produce some self-heat.
Physical photo of a typical NTC thermistor
There are various types of NTC thermistor in Analog Technologies, Inc., such as ATH10K1R25 and ATH100K1R25, etc.
To be continued…
If you are interested in our NTC thermistor, please visit our website:
http://www.analogtechnologies.com/thermistor.html
