The inrush current of an LED driver refers to the high current waste generated within a short period of time when the LED driver is started or powered on. The inrush current in an LED driver is typically caused by the charging of capacitors and magnetization of magnetic components.
When an LED driver is started, capacitors need to absorb a large amount of current from the power source to charge up and provide the required power to drive LED lights. At the same time, magnetization of magnetic components such as inductors and transformers also requires a large amount of current. These factors cause a temporary increase in the inrush current of the LED driver, which then gradually decreases after the capacitors are charged and the magnetic components are magnetized.
If the inrush current of an LED driver exceeds the tolerance range of the circuit design, it may cause damage to the power switch or cause the circuit breaker to trip.
There are several methods to suppress inrush current, including:
Using an NTC thermistor – An NTC thermistor is a temperature-sensitive resistor that generates heat when the initial inrush current passes through it, causing its resistance value to decrease. When the inrush current decreases to a steady state level, the NTC resistor cools down and returns to its resistance value. Therefore, by connecting an NTC thermistor in parallel with the device, the size of the initial inrush current can be limited.
Using a resistor to limit inrush current – A current-limiting resistor can be added to the circuit of a device or system to limit the size of the inrush current when it is turned on, so that it will not damage the device or system.
Using capacitor filtering – Connecting a capacitor in parallel with the device can smooth the initial start-up of the circuit and limit the size of the inrush current. When the inrush current decreases to a steady state level, the charging current of the capacitor reduces to near zero.
Using a relay for start-up – Connecting a relay in parallel with the device will automatically disconnect it after the initial inrush current passes when the device is started. This can reduce the size of the inrush current, thereby protecting the device or system.
In summary, there are many methods to suppress inrush current, and the most suitable method should be selected based on the specific application.
Reference：https://www.fsp-group.com/tw/knowledge-prd-8.html
Reference：http://www.switching.com.tw/supports-details-48.html
Reference：https://www.strongpilab.com/inrush-current-flicker-bulb/