In some applications, a compromise can be made to substantially lower the protection cost. Littelfuse offers PLED-9 devices that are designed to protect pairs of LEDs. Their switching voltage is higher so that the voltage of two LEDs in series will not activate them. The downside of this strategy is that if one LED in a pair fails open, the PLED device will bypass the current around the pair so that the second LED will also go dark. Depending on the exact application, this may be an acceptable trade-off. The PLED-13 takes this concept one more step, and protects three LEDs in series.