max amps,,, driving leds,


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  1. #1
    PICMAN's Avatar
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    Default max amps,,, driving leds,

    does this present a problem,,

    run total of 8 superbright leds, directly off pic16f84 pins ( with 330 ohms resistor, ) having posibly 6 on at once,

    is the 25 ma rating ,"PER" pin , or cumulitive, does this pose the threat or inevitibility of frying pic when 6 come on at one time ,

  2. #2
    egberttheone's Avatar
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    Red face

    As far as i know you can balast evry ouput with a rating of 25ma. done this my zelf.

  3. #3
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    Hi Picman,
    In the section "electrical specifications" of the data sheet you'll find pin, port, and package specs for absolute power. I don't have the '84 sheet here, so can't check the specs.

    Arch

  4. #4
    PICMAN's Avatar
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    ty ach for pulling that out for me, i knew there had to be absolute ratings aswell as the misleading front page saying 25 ms per pin .. knowing where to look put the answers where i could see em,.
    and for sake of finishing up the post, :

    max out put curent:
    port b 100 ma
    port a 50 ma

    which means stratigic design of what goes on which port, will allow for 6 to be "on" at once, reaching ,, not exceding 50 ma,,,

    puting all pins on high with an led stands a very good chance of blowing out the chip , if not a definate one, givin one led = 25 ma , 25 x 4 = 100 ma, over amping port a, rated for 50 ma

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