Total draw on 3.3vt interrupt pins

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  • March 15, 2018 at 1:36 pm #10914
    creeser
    Member

    I have four optical switches, each drawing 10ma on each 3.3vt output. Is the limit of 30ma a total amount or a per pin amount? Can’t tell from the schematics as I can’t calculate the total current draw of the rest of the items on the board.

    March 17, 2018 at 6:08 am #10917
    cmcgrath5035
    Moderator

    Are you using tinyGV8 or a DUE running G2Core?

    Are you interfacing off-the-shelf external drivers (or Solid State Relay) or a custom design? Most off-the-shelf units have an internal resistor in series with the opto-input that limits current.

    If you are interfacing an off the shelf opto input, I doubt you will get 10ma flow from a 3V port pin, in fact driving some off-the-shelf opto interfaces don’t work reliably driven directly from 3V logic.

    Onboard 3.3v is derived from Vin, which for most users is 24V but can be higher. The 24V to 3.3V regulator gets quite warm under normal operation.

    I see you (or perhaps the forum tool) tagged this as 3.3vt interrupt output; not sure what you mean by interrupt output.

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