Driving a transistor from HT12D

Discussion in 'The Projects Forum' started by André Ferrato, Dec 20, 2015.

  1. André Ferrato

    Thread Starter Member

    Apr 5, 2015
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    Hello, i intend to drive a transistor from HT12D outputs. I took a quick look through the datasheet and saw the Data Output Source Current and it's negative, this means that i cannot drive an NPN right ? Because i need to feed current to the NPN and as the Output is only sinking... Am i correct ?
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Looks like it will source ~1mA. Try 4.7K between the data pin and the base of an NPN whose emitter is tied to Vss (0V).

    holt.gif
     
  3. André Ferrato

    Thread Starter Member

    Apr 5, 2015
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    But the negative means that it's flowing on the opposite direction, so it can't feed an NPN or i am incorrect ?
     
  4. dl324

    Distinguished Member

    Mar 30, 2015
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    For that datasheet, negative means current out of the output and positive means current into the output.
     
  5. André Ferrato

    Thread Starter Member

    Apr 5, 2015
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    Oh i see.. but, when it says SOURCE, it means current getting out of the device right ? So by negative sign it means it's on the opposite direction, so it's SINKING, that's the way i see it or i am missing something ? Some semantics..
     
  6. dl324

    Distinguished Member

    Mar 30, 2015
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    Source is represented as a negative current, source is represented as a positive current. If you look at the output voltage, it will be apparent which way (conventional) current is going.
     
  7. André Ferrato

    Thread Starter Member

    Apr 5, 2015
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    I see, thanks dl324.
     
  8. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Semantics - exactly. Your interpretation would be correct except for one thing - the datasheet is not well written in an unambiguous way. DL is correct, the datasheet is confusing, and that's just something you have to live with when 1000 companies are writing datasheets with no absolute rules to follow.

    ak
     
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