Vague Mouser datasheet - LM317 max amp

Discussion in 'Power Electronics' started by Binary Buddha, Jul 20, 2017.

  1. Binary Buddha

    Thread Starter Member

    Sep 24, 2016
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  2. OBW0549

    Distinguished Member

    Mar 2, 2015
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    Nothing vague about it; under Maximum Ratings it says the maximum output current is internally limited. That means that the LM317's internal circuitry will limit the current (i.e., by reducing the output voltage) to a safe value. The maximum power dissipation of the chip is also internally limited to a safe value (presumably by monitoring the die temperature).

    Under Electrical Characteristics, the Maximum Load Current is listed as 1.5 amps minimum, 2.2 amps typical. That says the internal current limiting will allow you to draw at least 1.5 amps, and in most cases 2.2 amps.

    The safe thing to do (to avoid bitter disappointment) is to not count on getting any more than 1.5 amps from the device.
     
  3. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    In the electrical data there is clearly given the typical output current for two cases:

    LM317_max_current.png

    There is even a graph that shows the max output current for the different dropout voltages:

    LM317_max_current_versus_dropout_voltage.png

    Bertus
     
  4. crutschow

    Expert

    Mar 14, 2008
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    What do you consider is "kind of vague"?
     
    Last edited: Jul 20, 2017
  5. dl324

    AAC Fanatic!

    Mar 30, 2015
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    Conservative designers always use the worst case value specified by the manufacturer. Using anything else requires incoming testing to test for the desired characteristic(s).
     
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