LED strings stay illuminated when a single one fails

The PLEDxUx series is connected in parallel with each LED in a series string. Therefore if one LED fails, the PLED connected to it turns on and carries the current that would have gone through the failed LED. Providing reverse battery/power polarity protection for greater LED reliability, the series enables the remainder of the LED string to continue functioning. Suitable for dense board applications, the circuit protection devices maximise heat dissipation and layout flexibility.

Compatible with 1W LEDs (nominally 350mA at 3V), the PLEDxUx series offers higher reliability and lower maintenance requirements than earlier open LED protection solutions such as silicon controlled rectifiers (SCRs) and zener diodes. Often much larger devices, SCRs require additional components such as resistors to set the turn-on or trigger voltage, which will vary over temperature. Creating additional power dissipation once the LEDs they’re protecting fail open, Zener diodes are not rated for large DC currents, which can shorten life or lead to catastrophic failure.

Supporting PWM frequencies up to 10kHz, the PLEDxUx series enable the control of LED brightness without colour shifting. Additionally, by automatically resetting after power cycle, they allow for low maintenance and high reliability operation.

Betty Li, Product Manager, LED Protectors, Littelfuse, comments: “The PLEDxUx series is a great choice for outdoor applications that demand high reliability and low maintenance. It also offers comprehensive voltage coverage, especially higher voltage offerings that can allow designers to create a lower cost solution by placing a single PLED component across two or three LEDs, rather than a single LED.”

Supplied in standard tape and reel packaging, the RoHS compliant PLEDxUx series LED protectors are available in a 3x3 QFN package (5,000 unit quantities) or a DO‑214AA package (2,500 unit quantities). Samples are available now for bulk orders.