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voltage regulators

Discussion in 'General Electronics Discussion' started by glewis721, May 10, 2013.

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  1. glewis721


    Apr 30, 2013
    hi i'm just wondering about voltage regulators. does the output retain the same current as the input, or does it change?
    if so, then by how much?
  2. BobK


    Jan 5, 2010
    The current drawn from the input will be a little higher than the current at the output. This amount is the quiescent current specification for the regulator, and it is the current needed to operate the regulator.

  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    When operating within specs, the output voltage remains fixed to a value at or very close to the specified voltage. Within those constraints the output current can do anything.

    If it is a linear regulator, the input and output current will remain equal, except for the current actually required to operate the regulator itself.

    If it is a switchmode regulator, the input current will rise as the output current rises, and they will remain in proportion to each other (again after the exclusion of the current required to operate the regulator). However with a switchmode regulator the input and output powers are the same (at 100% efficiency) which means the input current can be higher or lower than the output current; the relationship is determined by the ratio of the input and output voltages.
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