Types of Thermistor : Difference between NTC and PTC

Thermistors are temperature sensitive resistors which exhibit significant resistance changes in response to temperature variations. They are also known as thermal resistors. Thermistors come in various sizes and shapes, such as rods, discs and beads. Let us explore 2 major types viz. NTC and PTC.

NTC stands for Negative Temperature Coefficient and PTC stands for Positive Temperature Coefficient.

1. NTC Thermistors

In NTC thermistors, resistance decreases as temperature increases. These are typically made of oxides of nickel, manganese, copper, cobalt, and other materials.

They are mainly used for temperature control and measurement applications. NTC thermistors are heated either by the external surroundings or through the internal flow of current.

This resistance change results in a current or voltage change. This change is then fed as input to an electronic system, where it’s processed based on the application.

2. PTC Thermistors

In PTC thermistors, resistance increases as temperature increases. They are often made of barium titanate.

They are often used to protect electronic circuits from high temperatures. This effect can be observed in electric motors overloaded due to short circuits or other issues.

Thermistor Manufacturers

Here are some well known manufacturers of thermistors.

1. AMWEI
2. EPCOS
3. Murata Electronics - Thermistor Manufacturer
4. Selco Products Co.
5. Semitec
6. Spectrum Control
7. US Sensors Corp.
8. Semitec
9. Vishay - Thermistor Manufacturer
10. GE

Conclusion:

By understanding the clear contrast between NTC and PTC thermistors, engineers can match the correct type to their application requirements. NTC thermistors excel in sensitive temperature measurement and current limiting, while PTC thermistors are better suited for protection and self regulating heating applications. Choosing between them hinges on the need for precise sensing versus resilience and safety in the circuit design.