The basics of a thermistor are pretty easy to understand. They are essentially a kind of semiconductor. Its name came from combing the words thermal and resistor. You can call it a resistor, but the resistance is measured based on the temperature.
So, what is a high-precision thermistor? These are basically very high-performance variants and give you precise reading, as you can probably tell from the name. Here is everything else you need to know.
Types of Thermistors
Mainly, there are two types of thermistors. You have NTC and PTC.
NTC stands for Negative Temperature Coefficient. The defining characteristic of these are they decrease the resistance as the temperature increases. That means the k value is negative here. You will see these are primarily used in datasheets and also component data.
The other type is PTC thermistors. Positive Temperature Coefficient or PTC thermistors do the opposite of NTCs. Their resistance increases with an increase in temperature. It means the k value is, of course, positive here.
A high-precision thermistor, for example, a high-precision NTC thermistor, will give you a very accurate reading and data. These data can be used in various ways and help engineers get precise control over operating temperatures.
They can have a resistance tolerance of 0.5% or even better in some cases. That gives you quite a lot of reliability, stability, and control over a long period of time.
There is a good reason why engineers and companies use these devices. There are a lot of benefits to using them in their products.
One of the most important ones is dependability. They are some of the most reliable components, and that’s why you will often see them being used in harsh and very difficult conditions.
They are stable and powerful as well. So, they are great for use in automobiles, security systems, battery packs, and more.
For as powerful as they are, these thermistors are also very compact. This makes them ideal for use in circuit boards and a lot of other places.
Due to their small size, there are also some inherent benefits. Primarily a high response time. It is helpful when you need quick feedback.
Compared to other temperature sensors, it’s also less expensive. And on top of that, if the RT curve is correct, then there is no need for additional calibrations during the installation process.
They can achieve a specific resistance at a specific temperature. This is based on the curve match.
The working principle behind a thermistor is quite interesting. Contrary to popular belief, a thermistor does not actually read anything. So, the temperature is what will modify the resistance of it.
What material the thermistor is made of is another factor to consider as well. Depending on which material is used, there can be resistance variation.
Also, these are nonlinear sensors. It means the relevance between resistance and temperature will not necessarily make a straight line when you plot them in a graph. The production of the thermistor is what specifies the line’s position and how much it may vary.
How to Choose a Thermistor
So, what goes into choosing a thermistor then? There are a few things to consider.
It is a no-brainer. You, of course, need one with a good temperature range. The better the temperature sensors, the better they will work in different applications. Not all industries will have the exact temperature range requirements.
Some can be high, and some, low. You, therefore, need to keep this in mind when choosing one. Typically, NTC thermistors can operate anywhere between 50-degree Celsius to 250-degree Celsius.
If you are going to need the thermistor to work for the long term, then stability becomes a very important factor. Having a stable one will help in this case and cause less drift.
Another no-brainer. Accurate readings are essential for obvious reasons. Getting one with the highest accuracy will ensure your readings are stable and the data represented is correct.
The packaging needs to be considered depending on what environment the thermistors will be used in. They can be potted in different housings and can be customized according to environmental needs. You can also have them glass encapsulated, or epoxy coated.
Frequently Asked Questions
1. What materials are used to make thermistors?
They are made from materials like cobalt, manganese, nickel, and even copper or iron in some cases. There can be a specific ratio when it comes to the mix of these materials to define the physical characteristics and dimensions of the thermistor.
2. What can make a thermistor stop working?
Handling damage can cause the resistor element and lead material to separate. This can make the thermistor stop working. Another reason a thermistor might stop working is excessive heat can also be another reason.
Drift in the resistance value is another common failure mode and can be caused by age. Last but not least, a short circuit can, of course, cause one to fail. But this is the least common
3. Are all thermistors ESD sensitive?
ESD stands for electrostatic discharge. They are not ESD sensitive by definition.
There you have it, and now you know what is a high precision thermistor and a whole lot more. They are a remarkable piece of technology that has seen widespread uses in different industries and continues to do so.