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zener and pn diode

Discussion in 'Electronics Homework Help' started by bhuvanesh, Mar 16, 2015.

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  1. bhuvanesh


    Aug 29, 2013
    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.
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    add 1) As far as I know zeners are not used in many rectifier circuits.
    add 2) A rectifier is designed to have no reverse current, therefore using zener diodes is contra-productive.
    add 3) a zener diode is a pn diode with a defined reverse breakdown voltage, that's what it makes special. When it comes to reverse breakdown, a standard pn diode has a comparatively high and not well defined breakdown voltage. Once a breakdown happens, the power dissipation will be high (P=V*I), possibly higher than that of a zener diode with a lower breakdown voltage. Did I say that breakdown should never occur in a rectifier?

    Here's a discussion on this topic with all the arguments.
    Last edited by a moderator: Mar 17, 2015
    davenn likes this.
  3. bhuvanesh


    Aug 29, 2013
    At breakdown voltage its supplying constant voltage with increase in reverse current,its apparent from transfer characteristics ,Then how do you say that zener dont have any reverse current .
  4. davenn

    davenn Moderator

    Sep 5, 2009
    Harald didn't
    you didn't correctly read what he said ....

    therefore, you don't use zeners as rectifiers
  5. bhuvanesh


    Aug 29, 2013
    YES,sorry for overlooking :(
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