A thermistor is a sensor resistor whose resistance changes with temperature. Based on their temperature coefficient, they are classified as positive temperature coefficient thermistors (PTC thermistors) and negative temperature coefficient thermistors (NTC thermistors). The resistance of a PTC thermistor increases with increasing temperature, while the resistance of an NTC thermistor decreases with increasing temperature. Both are semiconductor devices.

How does a thermistor work?
A thermistor remains in an inactive state for long periods of time. When the ambient temperature and current are in zone C, the thermistor's heat dissipation power and heat generation power are close, so it may or may not operate. At the same ambient temperature, the thermistor's operating time decreases dramatically as the current increases. At relatively high ambient temperatures, the thermistor exhibits a shorter operating time and lower holding and operating currents.

How do I generally choose the resistance value of a thermistor? A thermistor is a type of sensitive component, categorized by temperature coefficient into positive temperature coefficient thermistors (PTCs) and negative temperature coefficient thermistors (NTCs). Thermistors are typically sensitive to temperature, exhibiting varying resistance values at different temperatures. To find the right thermistor, you need to consider all aspects of the thermistor.

Start with the size of the device requiring the thermistor and the required physical properties, as well as the required standards.
1. Informing the NTC thermistor manufacturer of the relevant parameters and application requirements can help them provide the appropriate thermistor model, reducing selection headaches.
2. When selecting a thermistor, consider β tolerance and resistive limit, as these allow for adjustments to low and high resistance values.
3. Depending on the intended application of the NTC thermistor, you may also consider curve matching and thermistor interchangeability. When reviewing these factors, you may also need to consider cost and performance.
4. When searching for the right thermistor type, consider calibration.

What is the difference between thermal resistors and thermistors?
1.Different working principles
1) Thermistor: When the circuit is working normally, the temperature of the thermistor is close to room temperature and the resistance is very small. The series connection will not hinder the current in the circuit. When the circuit is overcurrent due to a fault, the temperature of the thermistor rises due to the increase in heating power. When the temperature exceeds the switch temperature, the resistance increases sharply instantly, and the current in the circuit quickly decreases to a safe value.
 2) Metal thermal resistor: The temperature measurement principle of the thermal resistor is based on the characteristic that the resistance value of the conductor or semiconductor changes with temperature, and measures temperature and temperature-related parameters. Thermistors are mostly made of pure metal materials. Currently, platinum and copper are the most widely used materials. Now, nickel, manganese and rhodium have been used to make thermal resistors. Thermistors usually need to transmit resistance signals to computer control devices or other secondary instruments through wires.

2.Different characteristics
1) Thermistor:
(1) The resistance temperature coefficient is 10-100 times larger than the metal temperature coefficient, and can detect temperature changes of 10-6C.
 (2) Wide operating temperature range: normal temperature device is suitable for -55-315 degrees Celsius, high temperature device is suitable for above 315 degrees Celsius (currently up to 2000 degrees Celsius), and low temperature device is suitable for -27-355 degrees Celsius.
(3) Small size, sufficient to measure the temperature of gaps, cavities and blood vessels that other thermometers cannot measure.
(4) Easy to use, the resistance value can be selected arbitrarily between 0.1 and 100K;
(5) Easy to process into complex shapes and can be mass-produced;
(6) Good stability and strong overload capacity.

2) Metal thermal resistor:
(1) Pressure spring type temperature sensor with good vibration resistance;
(2) High temperature measurement accuracy;
(3) High mechanical strength, resistant to high temperature and high pressure;
(4) Imported thin film resistor with stable and reliable performance.