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7805 regulator question

Discussion in 'Electronic Basics' started by Ken, Dec 18, 2004.

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  1. Ken

    Ken Guest

    There was not enough explanation on the spec sheet for me to
    understand its full workings: How high an input voltage do I need to
    ensure 5 volts out? E.g., will it output 5 volts if the input voltage
    is 5.5 volts? What volage figure tells me the minimum input voltage?

    Also, if the DC in is clean, will the DC out be clean?

    Ken
    (to reply via email
    remove "zz" from address)
     
  2. For a 7805, the datasheet recommends 7 to 20V.
    The point of the regulator is to 'clean up' the output. However, if the
    input dips below 7V, the output will reflect that.

    One tip in the datasheet is to use a capacitor on both the input and the
    output. A 0.33uF on input, and a 0.1uF on output is customary.

    --
    Regards,
    Robert Monsen

    "Your Highness, I have no need of this hypothesis."
    - Pierre Laplace (1749-1827), to Napoleon,
    on why his works on celestial mechanics make no mention of God.
     
  3. John Fields

    John Fields Guest

    ---
    According to the data sheet at:

    http://www.fairchildsemi.com/ds/KA/KA7805.pdf ,

    7V
     
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