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  1. #1
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    help for zener datasheet understanding

    Hello! I want to use a zener diode to protect the input pin of a microcontroller from overvoltages, but I really don't know which one to choose.
    The pin is fed by a 2200 ohm resistor, and after that, the zener to ground.
    I attached 2 sections of datasheets about 2 different zeners, they have very different values of Zzt, but i don't know which one is "better"
    I don't really understand in practice what the Zzt value means...
    For what I think, it's the resistance while it's in the breakdown region, so lower is better
    is this right?
    any advice is greatly welcome!
    Click image for larger version. 

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    Click image for larger version. 

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  2. #2
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    Re: help for zener datasheet understanding

    Izt means zener threshold current it is maximum for the particular rating shown in the data sheet



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  3. #3
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    Re: help for zener datasheet understanding

    Quote Originally Posted by yougarage View Post
    ... they have very different values of Zzt, but i don't know which one is "better"
    This is because the differential impedances Zzt have been measured at different break-through currents Izt. As larger Izt, as lower Zzt ; for relatively low currents the break-down characteristic gets steeper with rising current. I think the 2 diodes are comparable.



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