High-power LEDs can provide long working life, low power consumption, and low maintenance requirements that incandescent or CFL lamps cannot provide. These factors make LEDs increasingly popular in outdoor applications. However, LEDs are sensitive electronic components that can be easily damaged by transient overvoltages and overcurrents caused by system power on / off, electrostatic discharge, and nearby lightning strikes. In addition, switching power supplies that drive LEDs do not provide transient overvoltage or overcurrent protection for inductive LED lighting electronic ballasts.

In order to meet the needs of high-power LED lighting applications, LEDs are usually designed to be used in series of 5 to 20, because the power of a single LED cannot be made very large due to heat dissipation issues. The problem is that as long as any one of the LEDs in the series structure fails, the entire string of LEDs will fail together. In street light or airport runway lighting applications, a string of LED failures can cause the overall light brightness to dim or completely turn black, leading to unimaginable safety issues. In outdoor LED advertising display applications, this may produce white spots and lead to lost revenue. In any of these applications, a string of LED failures often leads to costly maintenance issues in outdoor applications.

解决 In order to solve this problem, many suppliers have successively introduced LED protection components of various sizes, such as Bourns, Littelfuse, TE (formerly Tyco Electronics), ON Semiconductor and Vishay.

The protection of traditional LEDs mainly considers anti-surge caused by lightning strikes and ESD effects, as well as preventing damage caused when the positive and negative poles of the power supply are reversed. However, for high-power LEDs used in outdoor lighting, it is also necessary to consider how the LED string works reliably and reduce maintenance costs. LED protection components introduced by suppliers such as Bourns and Lite can fully meet all of the above requirements. The LED protection element can not only prevent lightning, surge, and reverse connection, but also ensure that other LEDs emit light when an individual LED in the LED string is damaged and caused an open circuit.

LED protection elements can also effectively protect LEDs from nearby surge voltage / current sources such as ESD discharges. In addition, the LED protection element contains a reverse current diode, which protects the LED string from the reverse polarity of the power supply.

LED protection element is connected in parallel with each LED in the series. If an LED is open, the LED protection element connected to it will be turned on and the current that should have passed through the faulty LED will be directed to the LED protection element. This ensures that the other LEDs in the light string can work normally, so it is only a single LED that is extinguished, and the entire light string can still work normally, which greatly reduces the later maintenance costs of outdoor lighting.

When it is not turned on, the LED protection element only passes a few microamperes of current, so it will not affect the entire circuit. In the triggered state, it will carry the full current of the string and produce a voltage drop of approximately 1.3 volts.

The next half year will be the period when the demand for high-power LED protection changes from low production costs, high repair rates, high maintenance costs to low repair rates, high reliability, low maintenance, and even maintenance-free costs. Key timing.