White body LED protectors from Littelfuse enhance overall light engine efficiency



Littelfuse, a leader in circuit protection, has introduced an addition to the company's PLED Open LED protection devices line. The PLEDxSW Series LED Protector, unlike earlier PLED devices from Littelfuse that had black molded bodies, is molded from a white material, which makes it less noticeable in LED fixtures, particularly for indoor applications. It also reflects more light to improve overall light engine efficiency. This device provides an electronic shunt path when an LED in an LED string fails as an open circuit. PLED devices are connected in parallel with each LED in a series string. If one LED fails as an open circuit, the PLED connected to it turns on and carries the current that would have gone through the failed LED. This keeps the rest of the string operating, so only a single LED goes dark rather than the whole string. PLEDxSW Series LED Protectors are compatible with 1-, 2-, and 3-watt LEDs. Their low-profile, small-footprint package dissipates heat efficiently, so they're ideal for use in dense board applications. In contrast with earlier open LED protection solutions such as silicon controlled rectifiers (SCRs) and zener diodes, they offer higher reliability and lower maintenance requirements. For example, SCRs are usually large and require additional components like resistors to set the trigger or turn-on voltage, and their trigger voltage will vary widely over temperature. Zener diodes create additional power dissipation once the LEDs they're protecting fail open. They are also not rated for large DC currents, which can shorten life or lead to catastrophic failure. Typical applications of PLEDxSW Series LED Protectors include protection of lighting products that incorporate strings of high-brightness LEDs, including indoor lighting, aircraft/runway lights, and advertising signage. "Because they're designed specifically for protecting LEDs in applications that require high brightness, high reliability, and low maintenance, the new PLEDxSW Series provides circuit designers important advantages over SCRs and zener diodes," said Betty Li, product manager for LED Protectors. "They also have the advantage of a less-noticeable, molded white body that reflects more light to enhance the overall efficiency of the light engine." PLEDxSW Series LED Protectors offer these key design benefits: Protector is less visible in the LED fixture; reflects more light to enhance overall light engine efficiency Remainder of LED string can continue to function even if one LED fails as an open circuit Standard SMB package provides layout flexibility; maximum heat dissipation makes it ideal for dense board applications Low maintenance, high reliability Environmentally friendly product Availability PLEDxSW Series LED Protectors are available in quantities of 2,500 in tape and reel packaging. Littelfuse