Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Jk flip flop

  1. Jan 26, 2006 #1
    does anybody knows how to read the table or has any explanation for jk flip flop??any website recommended pls.........
  2. jcsd
  3. Jan 26, 2006 #2


    User Avatar

    Staff: Mentor

    Just check out the datasheet for a typical JK FF. It should have what you need. Here's a link to the Texas Instruments 74HC112 datasheet on Jameco's website:

    http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=296&M=SN74HC112N [Broken]
    Last edited by a moderator: May 2, 2017
  4. Jan 26, 2006 #3


    User Avatar
    Science Advisor

    That flip flop is probably a little more complicated than what he needs since it includes "pre" and "clr" inputs. The wikipedia article has a slightly simpler one:

    (the J-K flip flop truth table halfway down the page)

    The flip flop has 2 inputs, J and K (and also the clock). It remembers what the output Q was previously. On a clock edge, if J and K are 0, then the output Q remains unchanged. If J and K are 1, then the output Q flips from a 0 to a 1 or from a 1 to a 0. If K is 1 and J is 0, Q is set to 0, and if K is 0 and J is 1, Q is set to 1.
  5. Jan 26, 2006 #4
    What helped me was understanding fully basic idea of flip-flop and what S-R ff does, then J-K is just S-R with only difference in 11 input, where S-R goes unstable while J-K toggles (complements current state).

    But basically, as was said above: Q' is what you are "concerned" about, i.e. next state. Q' is a ff-particular function that depends on inputs J and K and present state Q. In other words, D and JK ff react (or have Q' function) differently to the same inputs and current state Q.
    Last edited: Jan 26, 2006
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook