Thermistor

Definition

A thermistor is a type of resistor whose resistance varies significantly with temperature. It is a temperature-sensitive resistor that is commonly used for temperature measurement, compensation, and control in various electronic devices and circuits.

5 Must Know Facts For Your Next Test

1. Thermistors are made of semiconductor materials, such as metal oxides, that exhibit a large change in resistance with a small change in temperature.
2. The resistance of an NTC thermistor decreases exponentially as temperature increases, making it highly sensitive to temperature changes.
3. Thermistors are used in various applications, including temperature measurement, temperature compensation, and thermal protection circuits.
4. The resistance-temperature relationship of a thermistor is typically non-linear and can be described by the Steinhart-Hart equation.
5. Thermistors can be used in combination with other circuit components, such as op-amps, to create temperature-sensing and control systems.

Review Questions

• Explain how the resistance of a thermistor varies with temperature and how this property is utilized in electronic circuits.
  • The resistance of a thermistor varies significantly with temperature, typically decreasing exponentially as temperature increases. This property is exploited in electronic circuits for temperature measurement, compensation, and control. Thermistors are made of semiconductor materials that exhibit a large change in resistance with a small change in temperature. By incorporating a thermistor into a circuit, the circuit's behavior can be adjusted based on the measured temperature, allowing for precise temperature monitoring and control in various applications.
• Describe the different types of thermistors and their applications in the context of resistance and resistivity.
  • There are two main types of thermistors: Negative Temperature Coefficient (NTC) and Positive Temperature Coefficient (PTC) thermistors. NTC thermistors, which are more commonly used, have a resistance that decreases as temperature increases. This makes them highly sensitive to temperature changes and useful for temperature sensing and control applications. PTC thermistors, on the other hand, have a resistance that increases as temperature increases, and they are often used for overcurrent protection and temperature compensation. Both types of thermistors rely on the relationship between resistance, resistivity, and temperature to function effectively in electronic circuits and devices.
• Analyze how the resistance-temperature relationship of a thermistor, as described by the Steinhart-Hart equation, allows for accurate temperature measurement and control in various applications.
  • The resistance-temperature relationship of a thermistor is typically non-linear and can be described by the Steinhart-Hart equation. This equation allows for the accurate calculation of temperature based on the measured resistance of the thermistor. By incorporating a thermistor into a circuit and using the Steinhart-Hart equation to interpret the resistance data, electronic devices can precisely measure and control temperature in a wide range of applications, such as temperature monitoring, thermal management, and temperature-sensitive control systems. The ability to accurately relate the resistance of a thermistor to the corresponding temperature is a key factor in its widespread use for temperature measurement and control in various industries and technologies.

Related terms

Resistance:

The measure of the opposition to the flow of electric current in a circuit, measured in ohms (Ω).

Resistivity:

A material property that quantifies how strongly a material opposes the flow of electric current, measured in ohm-meters (Ω·m).

Negative Temperature Coefficient (NTC): A type of thermistor whose resistance decreases as temperature increases, commonly used for temperature sensing and control.