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How do you use NTC thermistors for inrush current limiting?
To limit inrush current, an NTC thermistor is placed between the power supply and system (see Figure 1). Upon power on, the NTC thermistor provides high resistance to limit inrush current. As the inrush current drops, the NTC thermistor self-heats and its resistance drops to a low enough value to pass current through.
Where is inrush current limiter used?
An inrush current limiter is a component used to limit inrush current to avoid gradual damage to components and avoid blowing fuses or tripping circuit breakers. Negative temperature coefficient (NTC) thermistors and fixed resistors are often used to limit inrush current.
How do inrush current limiters work?
The nature of the inrush current limiter to self-heat as an increasing amount of current is applied, which generates heat, causes resistance to drop, allowing the current to flow freely. This self-heating effect is the underlying reason that allows the inrush current limiter to work effectively.
What is power thermistor?
A Power Thermistor, also called Power NTC or inrush current limiter, is an electronical component which suppresses inrush currents of electric circuits. Switching power supplies, AC motors, and lighting ballasts can induce an inrush current of more than 100 times the nominal current when the circuit is switched on.
What is thermistor and its limitation?
Non-linearity in resistance vs temperature characteristics. Unsuitable for wide temperature range. Very low excitation current to avoid self-heating. Need of shielded power lines, filters, etc.
What is the working principle of thermistor?
The thermistor works on the simple principle of change in resistance due to a change in temperature. When the ambient temperature changes the thermistor starts self-heating its elements. its resistance value is changed with respect to this change in temperature.
What is the main advantage of a thermistor?
They are more sensitive than other temperature sensors. High sensitivity allows them to work well over a small temperature range. They’re low cost and therefore cheap to replace. They provide a fast response.
What is thermistor and its application?
Thermistors are used as temperature sensors. They can be found in every day appliances such as fire alarms, ovens and refrigerators. They are also used in digital thermometers and in many automotive applications to measure temperature.
How are NTC thermistors used for inrush current limiting?
It is called an inrush current, and without protection, it may destroy a semiconductor device or have a harmful effect on the service life of a smoothing capacitor. NTC thermistors are used as ICLs (inrush current limiters) to protect circuits of electrical and electronic devices against inrush currents easily and effectively.
Where are the inrush current limiters usually located?
Inrush current limiters are typically installed in either locations A&B or C&D and depending on applications sometimes only on location A or C. Figure 1: NTC-based limiting circuit. To limit inrush current, an NTC thermistor is placed between the power supply and system (see Figure 1).
How are NTC thermistors used in switch mode power supply?
The following are details of sample applications of NTC thermistors for inrush current limiting. Inrush current limiting in a switch-mode power supply (SMPS) Various switch-mode power supplies (SMPS) – which are small, lightweight, and high-performance – are often used as power supplies of electronic devices.
How is inrush current limiting used in SMPS?
Inrush current limiting in a switch-mode power supply (SMPS) Various switch-mode power supplies (SMPS) – which are small, lightweight, and high-performance – are often used as power supplies of electronic devices. At the time of powering on an SMPS, the device is charged with an inrush current with a high peak to charge a smoothing capacitor.