open collector output split

Discussion in 'General Electronics Chat' started by by_ron1, May 27, 2015.

  1. by_ron1

    Thread Starter New Member

    May 27, 2015
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    I want to split the signal coming out of an open collector transistor output.
    My understanding is that the sensor will pull down to 1.0V with a 10K Ohm pull up resistor
    As simple as putting a 5K Ohm pull up resistance ?
    Thoughts ?
     
  2. ScottWang

    Moderator

    Aug 23, 2012
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    Could you provide any practical input signal and output signal and the next stage or device, how are the V/I?
     
  3. Papabravo

    Expert

    Feb 24, 2006
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    The concept you are describing sounds like nonsense. You don't "split" logic signals, but you can drive multiple loads. The pullup for an open collector (open drain) has an upper limit and a lower limit. Check out the following article.
    http://www.ti.com/lit/an/slva485/slva485.pdf
    You could have eliminated the ambiguity with a schematic.
     
  4. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    When you say "split", what do you mean? Do you want to send an identical signal to two different locations, or do you want to divide its amplitude in half?

    Think.....then write.

    ak
     
  5. by_ron1

    Thread Starter New Member

    May 27, 2015
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    I want to send identical signal to two locations (tow displays)
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
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    We're not mind readers!

    It could be as simple as connecting the loads in parallel, they may need to be diode-or'ed or you may need to separately buffer the 2 signal paths.

    Without a bit of detail there's just no way to tell.
     
  7. Papabravo

    Expert

    Feb 24, 2006
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  8. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Gates and other logic devices have specified output current capabilities. If this is not ECL or some other structure where there should be only one load per output, or very high speed where characteristic impedance mismatches cause reflections, then you probably can drive two destinations with one source just by hooking them up. If this is all on one pc board with a ground plane, that's all it takes. If the connections are over wires, be sure to have one ground return wire per signal wire.

    ak
     
  9. ian field

    Distinguished Member

    Oct 27, 2012
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    An open collector output probably isn't microwave.

    The TS mentioned "tow display" - google didn't find anything relevant looking.
     
  10. AnalogKid

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    Aug 1, 2013
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    his typo - two displays
     
  11. ian field

    Distinguished Member

    Oct 27, 2012
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    Wondered why I'd never heard of it.
     
  12. Papabravo

    Expert

    Feb 24, 2006
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    Of course not. I was trying to cite an example where splitting was a relevant concept.
     
  13. ian field

    Distinguished Member

    Oct 27, 2012
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    The TS was so vague, you have to get right down to eliminating things it isn't.
     
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