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Datasheet confusion

Discussion in 'Electronic Basics' started by Rikard Bosnjakovic, Feb 28, 2007.

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  1. I have two datasheets describing the transistor 2N3906. Consider these
    pdf-files:

    http://www.datasheetarchive.com/datasheet.php?article=3743092
    http://www.datasheetarchive.com/datasheet.php?article=3743093

    The first one tells me the dissipation (Pd) is 625mW, while the second
    tells me Pd is 350mW. I'm aware of the fact that this may be because
    two different companies made hem, but are components really allowed
    the same brand if their characteristics differ?

    I'm asking because I don't have any 2N3906 at home (and I'm not gonna
    order new ones) so I'm looking for replacements. But if their values
    differ - how am I supposed to know which replacements to look for?
     
  2. Phil Allison

    Phil Allison Guest

    "Rikard Bosnjakovic"

    ** No you do not - they are not data sheets.


    ** Those are second party re-listings.

    Likely compiled by 12 year old Mexicans.



    ** Original manufacturers data sheets for individual types are there if you
    bother to look.

    Shame YOU are too damn lazy to feed a number into Google.



    ** For the same type number in the exact same package - there is no
    significant variation in Pd.




    ....... Phil
     
  3. Bob Eld

    Bob Eld Guest

    The 3906 is a small signal transistor. It is not meant to dissipate any
    significant power. If you keep the dissipation below a couple of hundred
    milliwatts you should be ok. If you are asking about 650mW, you are using
    the WRONG part regardless of what some data sheets may say. Be safe and do
    not exceed the lowest listed value regardless of manufacturer. If you need
    more power, pick a different part.
     
  4. Neither of those compilations is actually a data sheet.
    They are collections of interpretations of the information
    from data sheets. The first gives a power limit and the
    conditions that apply to that limit (25 C ambient). the
    second gives a power limit but no conditions, so it may
    apply to a completely different situation, like maximum
    rated ambient temperature.

    These compilations are handy to find somewhat similarly
    rated devices, to start a selection process (for anything
    with more at stake than a hobby project), but the final
    decision should always include looking at the actual
    manufacturer's data sheet, and reading all the fine print.
    The same specification often means different things when you
    take the notes and specified test conditions into account.

    The universe is complicated. Sorry.
     
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