zener and pn diode confusion

[Bhuvanesh123]

The transfer characteristics of zener and pn diode looks same in reverse bias, i have asked few why in many rectifier circuits zener is used.i got answer like, it wont burn up in high reverse current like pn diode . why zener is special than pn diode.

 

[panda1234]

with zener we can easily make a circuit that is very little ripple of voltage in general zener diode like a voltage source in saturation.

 

[betwixt]

Zeners are not normally used in rectifier circuits. They are normally used in situations where a constant voltage is needed when the current through them may vary.

Up to breakdown voltage, the reverse characteristics of Zener and normal PN junctions are similar. The difference is that doping materials are added to control the breakdown voltage. A PN diode will try to hold back reverse polarity until the point where the barrier regions can no longer maintain structure and it then starts to conduct, usually with permanent damage occurring. The voltage is not exactly predictable from one device to another. A Zener is doped to allow controlled conduction at a desired voltage where the current can be resticted to prevent overheating or crystal damage.

Brian.

 

[Audioguru]

I think the symbol of a zener diode is confused with the symbol of a Schottky rectifier diode.

With a high reverse bias, a zener diode conducts with its rated zener voltage across it. So if the current is high then of course it will burn up.
A rectifier diode will not conduct if the high reverse bias does not exceed its maximum allowed rating so of course it will not even get warm.