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  1. #1
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    7 segment LED with integrated zener diode .

    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 ?

    Thanks.

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  2. #2
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    Re: 7 segment LED with integrated zener diode .

    Hi,

    I see no reason, why the zener can't be external.

    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...

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



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  3. #3
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    Re: 7 segment LED with integrated zener diode .

    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.

    Brian.
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    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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  4. #4
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    Re: 7 segment LED with integrated zener diode .

    Thank Klaus and Betwixt,
    Your information is very helpful. I check with my partner on the design to solve my problem.

    Regards.



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