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Zener diode datasheet, how does company choose test current?

Discussion in 'Homework Help' started by wiwa_ze, Aug 15, 2010.

  1. wiwa_ze

    wiwa_ze New Member

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    I've seen many datasheet about zener diode for regulator voltage.
    And zener voltage depends on test current, right?
    So I want to know how to manufacturing company choose test current?
     
  2. Dragon Tamer

    Dragon Tamer Member

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    The voltage of a zener diode is constant, it won't change if the current changes. The manufacturer does not "choose" the current of a zener, it is measured as the maximum amount of current that the zener will allow to flow through itself without being damaged.
     
  3. wiwa_ze

    wiwa_ze New Member

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    Thanks Mr. Dragon, for your answer.
    But what is the origination of Izt and Vzt??
     
  4. dave

    Dave New Member

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  5. Jony130

    Jony130 Active Member

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    Well, almost all manufacturers use 5mA as a test current.
    Why it's 5mA I don't now. Maybe its has something to do with "knee" of a Zener diode.
    And to make sure that the Zener diode will produce the Zener voltage the current must be at least equal to test current.

    http://www.electro-tech-online.com/threads/zener-diode-test-current-izt-help.39227/#post311687
     
    Last edited: Aug 16, 2010
  6. crutschow

    crutschow Well-Known Member Most Helpful Member

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    The manufacturers choose a convenient current that's well above the "knee" of the Zener, so the test is well into the flat portion of the zener voltage versus current region. Some small zeners have a low current knee, so they are tested at a lower current, whereas high power zeners are generally tested at a higher current.
     
  7. crutschow

    crutschow Well-Known Member Most Helpful Member

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    That is not correct. They test at a much lower current, then that.
     
  8. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Sorry, but it's a LONG way from constant - the datasheet will usually even provide a graph showing the voltage changes with current.
     
  9. wiwa_ze

    wiwa_ze New Member

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    Thank you very much.
    It's cleared.
     

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