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Zener diode- Invincible?

  1. Jan 19, 2012 #1
    Hey everyone! I was just wondering why a Zener diode doesn't get damaged whereas an ordinary p-n junction diode does, when reverse-biased under sufficient voltage. In both diodes, when reverse-biased, there is a dislodging of valence electrons of the host atom. So, why does this damage the p-n junction diode alone, while the Zener diode remains safe?
    Last edited: Jan 19, 2012
  2. jcsd
  3. Jan 19, 2012 #2
    The Zener can be destroyed by overheating due to too much current or inadequate cooling or both.

    The ordinary diode also breaks down just like a Zener but is typically in a circuit that isn't designed to limit the breakdown current. In this case the diode is also destroyed by too much breakdown current.

    If you take an ordinary diode and limit the current it will not be destroyed by exceeding the breakdown voltage.
  4. Jan 19, 2012 #3


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  5. Jan 20, 2012 #4
    Whatever makes you think that?

    Of course it does, if anything the situation is the other way round.

    When we connect a diode in zener mode we always use a current limiting resistor (or source) in series.
    If we don't do this, excess current will flow and destroy our diode.

    When we connect a diode as a rectifier we employ one with a high enough blocking rating to prevent breakdown and reverse current flowing, thus there is no need for a current limiting resistor.

    go well
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