Asynchronous JK flip-flop / JK latch?

Discussion in 'General Electronics Chat' started by Tous, Aug 28, 2013.

  1. Tous

    Thread Starter New Member

    Aug 28, 2013
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    Hey,

    Does anyone know of an IC to accomplish the logic outlined on this page: http://www.rs-flip-flop.com/index.php?page=jk


    Should I just construct this circuit out of NOR gates? I don't have an oscilloscope to verify I don't end up with any kind of jitter on my output. It will be a lot easier if there's a JK FlipFlop that has asynchronous inputs that behave the same as its clocked inputs. The datasheets I've read don't toggle on both async inputs HIGH.

    If its unclear, I need a logic for a 2 input, 1 output circuit where Input1 positive edge triggers the output HIGH and Input2 Positive edge triggers the output LOW. a clocked jk flipflop seems to work exactly this way but I want an asynchronous circuit and I can't find an IC that toggles on asynchronous Inputs both HIGH.

    Any thoughts?
    Thanks for reading,
    Tous
     
  2. panic mode

    Senior Member

    Oct 10, 2011
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    why can't you create two edge-detect circuits and use them to trigger simple RS (pair of NANDs or NORs)?
     
  3. Tous

    Thread Starter New Member

    Aug 28, 2013
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    I just looked up edge-detect circuits. Thanks for making me aware of this. I'm learning as I go.

    That's not bad, and may work, but it's just reducing the problem isn't it? The possibility of a simultaneous Set and Reset High ("a restricted combination") is still there?
     
  4. Tous

    Thread Starter New Member

    Aug 28, 2013
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    0
    Hmm.. As I read the page I linked more, the author claims this is a very stable circuit. Anyone have any thoughts on the matter?

    I guess I'll give it a shot. If anyone knows of a IC or better solution to accomplish this asynchronously, please let me know.

    Input1 Input2__Output
    __0____ 0____No Change
    __0____1_____1
    __1____0_____0
    __1____1_____Toggle
     
  5. panic mode

    Senior Member

    Oct 10, 2011
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    I am too lazy to look into it, if you like build or simulate it and see if it works.
    did you consider PIC10F?
     
  6. WBahn

    Moderator

    Mar 31, 2012
    17,720
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    And for a very good reason. If the FF toggled if both asynchronous inputs were HI, then as soon as it did so it would toggle again, because both asynchronous inputs are HI, telling it to toggle. And so on and so on. So the chip would simply oscillate at it's fastest possible speed. This is actually how some oscillators work -- known as ring oscillators.
     
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