Why Does a Zener Diode Withstand Reverse Biasing When Ordinary Diodes Fail?

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Discussion Overview

The discussion revolves around the differences in behavior between Zener diodes and ordinary p-n junction diodes when subjected to reverse biasing, particularly under conditions of sufficient voltage. Participants explore the mechanisms that allow Zener diodes to withstand reverse bias without damage, while ordinary diodes typically fail under similar conditions.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why Zener diodes remain undamaged under reverse bias while ordinary diodes do not, noting that both involve dislodging valence electrons.
  • Another participant explains that Zener diodes can be destroyed by overheating due to excessive current or inadequate cooling, while ordinary diodes can also break down but are often in circuits not designed to limit breakdown current.
  • A third participant suggests that if an ordinary diode has current limited, it will not be destroyed by exceeding the breakdown voltage.
  • One participant challenges the initial premise, stating that Zener diodes can indeed be damaged if not properly protected with a current limiting resistor, and contrasts this with the use of ordinary diodes in rectifier applications where high blocking ratings prevent breakdown.

Areas of Agreement / Disagreement

Participants express differing views on the conditions under which Zener and ordinary diodes fail when reverse-biased. There is no consensus on the mechanisms or protections necessary for each type of diode.

Contextual Notes

Participants discuss the importance of current limiting in protecting both types of diodes, but the specifics of how each diode type behaves under reverse bias and the conditions leading to failure remain unresolved.

jobsism
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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?
 
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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.
 
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.

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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