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Have you ever experienced a power surge or circuit breaker tripping when turning on an appliance or electronic device?

This could be due to inrush current, which is the initial surge of current that flows through a circuit when power is first applied. To prevent this surge from damaging the circuit or components, an NTC (Negative Temperature Coefficient) inrush current limiter can be used. This type of limiter is made of a thermistor that has a decreasing resistance as its temperature rises.

When power is first applied, the thermistor's low resistance allows current to flow freely, limiting the initial surge of current. As the current decreases, the thermistor's temperature rises, increasing its resistance and limiting the current further.

NTC inrush current limiters can be used in a variety of applications, including power supplies, motor controllers, and LED lighting. When selecting an NTC limiter, it's important to consider the circuit's operating voltage, current, and temperature range, as well as the thermistor's time constant and maximum power rating.

Tips for Using NTC Inrush Current Limiters

• Size the NTC limiter correctly: Choose an NTC limiter with the appropriate current and voltage ratings for your circuit. Oversizing or undersizing the limiter can lead to ineffective protection or even damage to the circuit.
• Consider the thermistor's time constant: The time constant is the amount of time it takes for the thermistor's resistance to change to 63.2% of its final value. This should be considered when selecting an NTC limiter to ensure it can handle the current surge for the required amount of time.
• Mount the NTC limiter correctly: The limiter should be mounted close to the circuit being protected to ensure its effectiveness. It should also be mounted in a location with good airflow to allow for proper cooling and prevent overheating.
• Test the NTC limiter: Before using the NTC limiter in your circuit, test it to ensure it's working correctly. This can be done using a multimeter to measure the resistance of the thermistor at room temperature and at the expected operating temperature.

Final Thoughts

NTC inrush current limiters are a simple and effective way to protect circuits and components from inrush current damage. By selecting the appropriate limiter and following proper installation and testing procedures, you can ensure your circuit operates safely and reliably.

We hope this article has been helpful in providing you with the knowledge and tips you need to use NTC inrush current limiters in your projects. Happy circuit building!