What is PTC type thermistor?
What is PTC type thermistor?
PTC thermistors are resistors with a positive temperature coefficient, which means that the resistance increases with increasing temperature. PTC thermistors are divided into two groups based on the materials used, their structure, and the manufacturing process. The second group is the switching type PTC thermistor.
How does a PTC thermistor react?
A PTC thermistor works a little differently. When temperature increases, the resistance increases, and when temperature decreases, resistance decreases. This type of thermistor is generally used as a fuse.
How does a PTC fail?
Repetitive tripping of ceramic PTC (even within specified power handling capabilities). Leads become detached and small sparks can occur between the detached lead and the ceramic. Fails open. When micro-cracks are present due to power handling inside the ceramic bulk, the number of cycles can also be limited.
What are thermistors made of?
Thermistors are made from semiconductor materials, typically metallic oxides, using cobalt, manganese, or nickel. The temperature–resistance relationship in a thermistor is nonlinear and negative, as shown in Equation 1.10. 1.
What is the purpose of potential divider?
A potential divider is a simple circuit that uses resistors to supply a variable ‘potential difference’ (i.e. voltage). This can be used for many applications, including control of temperature in a fridge or as audio volume controls.
How can you tell the difference between NTC and PTC thermistors?
For an NTC thermistor, as temperature increases, resistance decreases. For a PTC thermistor as temperature increases, resistance increases.
What is the use of potential divider with NTC thermistor?
Potential Divider with NTC Thermistor. A thermistor is a temperature sensitive resistor where its resistance changes with respect to temperature. Made from a polycrystalline silicon material, it provides the greatest resistance change with small changes in temperature. It connects as a part of a potential divider, also known as voltage divider,…
Why are PTC thermistors placed in series?
PTC thermistors are typically placed in series with a circuit as inline and resettable fuses to protect against overcurrent situations. When over current situation occur its temperature repeatedly increases causing the thermistor resistor to increase as well. There are two varieties of PTC:
How does a thermistor connect to a circuit?
It connects as a part of a potential divider, also known as voltage divider, network in a circuit. Of all the different types of temperature sensing devices, the thermistor is the most sensitive and provides the greatest change in resistance with changes in temperature.
How does temperature affect voltage divider?
If you use the thermistor as the “top” leg of the potential divider, the voltage will increase as the temperature increases. If you use a thermistor as the bottom leg of the voltage divider, then the voltage will decrease as the temperature increases. Either method is valid.
