High-power LEDs can provide long operating life, low power consumption and low maintenance requirements that incandescent or CFL lamps cannot provide. These factors have made LEDs increasingly popular in outdoor applications. However, LEDs are sensitive electronic components that are easily damaged by transient overvoltages and overcurrents caused by system on/off, electrostatic discharge, and nearby lightning strikes. In addition, switching power supplies that drive LEDs do not provide the transient overvoltage or overcurrent protection of 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 with 5 to 20, because the power of a single LED cannot be made very large due to heat dissipation. But the problem is that as long as any one LED in the series structure fails, the entire string of LEDs will fail together. In a streetlight or airport runway lighting application, the failure of a string of LEDs may cause the overall light brightness to dim or completely black, causing unimaginable safety issues. In outdoor LED advertising display applications, this can produce white spots and lead to lost revenue. In any of the above applications, failure of a string of LEDs often leads to costly maintenance problems in outdoor applications.

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

The protection of traditional LED mainly considers the surge caused by lightning strike and ESD, and the damage caused by the positive and negative poles of the power supply. However, for high-power LEDs used in outdoor lighting, it is also necessary to consider how LED strings work reliably and reduce maintenance costs. LED protection components introduced by suppliers such as Bourns and Ryder can fully meet all the above requirements. The LED protection element can not only prevent lightning strike, surge and reverse connection, but also ensure the normal light emission of other LEDs when there is an individual LED damage in the LED string.

The LED protection element can also effectively protect the LED from surge voltage/current source such as adjacent lightning strike and ESD discharge. In addition, the LED protection element contains a reverse current diode, which protects the LED string from the reverse polarity of the power supply.

An 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 turn on and direct the current that should have passed through the faulty LED to the LED protection element. This ensures that the other LEDs in the light string can work normally, so only a single LED is turned off, and the entire light string can still work normally, greatly reducing the maintenance cost of outdoor lighting.

When 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 light string and produce a voltage drop of about 1.3 volts.

The next six months will be the period when the demand for high-power LED protection changes from low production cost, high maintenance rate, high maintenance cost to low maintenance rate, high reliability, low maintenance and even maintenance-free cost, and it is also the key time for LED protection components to be accepted and recognized by the market.