Hi all,
I have requirement for a display PCBA, It has some 7-seg LEDs display (used for home appliance).
I met a problem: after a certain time, one or several segments were broken and no light. (error rate about 0.5%)
To solve this trouble, our supplier (an IDH) who designed my PCBA said he must design the new 7-seg LED with integrated Zener diode to avoid damage by EM environment.
To integrated zener, he have to use a custom led by open a new mold for LED.
I tried to find some led built-in zener on internet, no many LED use this solution. So, do you think he said correct or not ?
I don't think EM (HF) is a problem, I rather think it's overvoltage, overcurrent or overheat.
But LEDs are rather robust, but they don't like reverse voltage.
Please show photos of display, PCB, wiring, mounting...
LEDs are already constant voltage devices so there is no point in placing a Zener across them. If reverse voltage may be an issue, a normal diode will work just as well. As Klaus stated, the problem isn't likely to be over voltage (where a Zener might help) but over current which is a design issue a diode can't fix.