Flip Flop Conversion

john March 7, 2012 53 Comments

For the conversion of one flip flop to another, a combinational circuit has to be designed first. If a JK Flip Flop is required, the inputs are given to the combinational circuit and the output of the combinational circuit is connected to the inputs of the actual flip flop. Thus, the output of the actual flip flop is the output of the required flip flop. In this post, the following flip flop conversions will be explained.

 

As told earlier, J and K will be given as external inputs to S and R. As shown in the logic diagram below, S and R will be the outputs of the combinational circuit.

The truth tables for the flip flop conversion are given below. The present state is represented by Qp and Qp+1 is the next state to be obtained when the J and K inputs are applied.

For two inputs J and K, there will be eight possible combinations. For each combination of J, K and Qp, the corresponding Qp+1 states are found. Qp+1 simply suggests the future values to be obtained by the JK flip flop after the value of Qp. The table is then completed by writing the values of S and R required to get each Qp+1 from the corresponding Qp. That is, the values of S and R that are required to change the state of the flip flop from Qp to Qp+1 are written.

SR Flip Flop to JK Flip Flop
SR Flip Flop to JK Flip Flop

This will be the reverse process of the above explained conversion. S and R will be the external inputs to J and K. As shown in the logic diagram below, J and K will be the outputs of the combinational circuit. Thus, the values of J and K have to be obtained in terms of S, R and Qp. The logic diagram is shown below.

A conversion table is to be written using S, R, Qp, Qp+1, J and K. For two inputs, S and R, eight combinations are made. For each combination, the corresponding Qp+1 outputs are found ut. The outputs for the combinations of S=1 and R=1 are not permitted for an SR flip flop. Thus the outputs are considered invalid and the J and K values are taken as “don’t cares”.

JK Flip Flop to SR Flip Flop
JK Flip Flop to SR Flip Flop

As shown in the figure, S and R are the actual inputs of the flip flop and D is the external input of the flip flop. The four combinations, the logic diagram, conversion table, and the K-map for S and R in terms of D and Qp are shown below.

SR Flip Flop to D Flip Flop
SR Flip Flop to D Flip Flop

D is the actual input of the flip flop and S and R are the external inputs. Eight possible combinations are achieved from the external inputs S, R and Qp. But, since the combination of S=1 and R=1 are invalid, the values of Qp+1 and D are considered as “don’t cares”. The logic diagram showing the conversion from D to SR, and the K-map for D in terms of S, R and Qp are shown below.

D Flip Flop to SR Flip Flop
D Flip Flop to SR Flip Flop

J and K are the actual inputs of the flip flop and T is taken as the external input for conversion. Four combinations are produced with T and Qp. J and K are expressed in terms of T and Qp. The conversion table, K-maps, and the logic diagram are given below.

JK Flip Flop to T Flip Flop
JK Flip Flop to T Flip Flop

D is the external input and J and K are the actual inputs of the flip flop. D and Qp make four combinations. J and K are expressed in terms of D and Qp. The four combination conversion table, the K-maps for J and K in terms of D and Qp, and the logic diagram showing the conversion from JK to D are given below.

JK Flip Flop to D Flip Flop
JK Flip Flop to D Flip Flop

In this conversion, D is the actual input to the flip flop and J and K are the external inputs. J, K and Qp make eight possible combinations, as shown in the conversion table below. D is expressed in terms of J, K and Qp.

The conversion table, the K-map for D in terms of J, K and Qp and the logic diagram showing the conversion from D to JK are given in the figure below.

D Flip Flop to JK Flip Flop
D Flip Flop to JK Flip Flop
Comments
  • June 19, 2015

    Thank you so much for these flip flop conversions

  • aravind
    May 18, 2015

    there is a mistake in the SR flipflop to JK flipflop where S=(~J)*Qp.

  • ALOK
    April 11, 2015

    THANKS

  • snehrahul
    March 31, 2015

    How to convert sr flip flop to t flip flip?

  • RAHUL KESHRI
    December 18, 2014

    In conversion of sr to jk flipflop
    Y r we not paring with don’t cares..???
    Since we are pairing with don’t cares in each conversion…

    Reply me on my mail id its urgent to know…

    Thanks

  • Navneet Toor
    December 6, 2014

    very helpful……. great job

  • November 28, 2014

    this is awsome.it is very helpfull to me for checking my task is correct or not……..thanks a megaton

  • Abhi
    November 28, 2014

    yeah this is very helpful
    but one mistake is there.in SR toJK flip flop the eqn for s will be S=J*Qp bar .

  • Shreya
    November 26, 2014

    very easily explained.Thanks a lot

  • Amit
    November 19, 2014

    Very helpful….i clear this topic..

  • keshav sharma
    November 12, 2014

    it is very useful 4 me thanks for u

  • Umesh
    August 24, 2014

    Wonderful explanation. Easy language used. Very easy to learn! Thanks a ton!

  • muhammad haris
    May 8, 2014

    Its very clear and understandable , thank u so much.

  • Rajesh Hanswal
    May 6, 2014

    It will be S=J*(Q_p)’ in S-R to J-K conversion instead of J’*(Q_p) this error is in the K-Map Solution for S.
    Otherwise it is very good content and very useful..
    Thanx

  • May 1, 2014

    it is very useful to me thanks………….

  • Debadrito
    April 20, 2014

    These information are very helpful for those who want to know about flip flop. It is wonderful.

  • April 11, 2014

    This was wonderful. I am going to tell my classmates about it. Our professor just couldn’t seem to explain it this clearly, so this really helped. Thanks!

  • March 30, 2014

    In the SR Flip Flop to D Flip Flop
    there is a mistake in the R K-Map
    the term (1) should be “1” not “0”

  • sumanti
    February 28, 2014

    found it helpful for writing exam …
    ACTUALLY COYING DURING THE EXAM 😀
    KEEP IT UP !!!!!!!

  • Tarek Jreidini
    December 17, 2013

    thank you so much my exam’s in 4 hours i needed this

  • Tiago
    December 16, 2013

    Awesome. Thanks. Althought there’s an error on the JK Flip Flop to D Flip Flop table. Last line. Qp+1 should be 1 and not 0. But the corresponding JK Inputs are correct. This said, everything is good except Qp+1.

  • Tarun
    December 1, 2013

    Thanks A bunch…:-)

  • November 28, 2013

    was really helpful…….thanks a bunch

  • Bharatish Puranik
    November 20, 2013

    That Was awesome….gracias…

  • rahul kumar
    October 27, 2013

    please try to keep the solution for D-ff to T-ff conversion

  • vijay kumar
    October 21, 2013

    can i have details about D flip flop to SR flip flop using NOR gates only.

  • isabel
    October 12, 2013

    muy buen contenido …gracias

  • Jeny
    October 5, 2013

    thank u very much…!!
    its up to the point and brief.

  • September 22, 2013

    very helpful.thankyou

  • JITENDRA KHATIK
    August 19, 2013

    simply awsom…..helpfull…

  • Terry
    July 26, 2013

    Very useful! Thank u very much!

  • gyanendra
    July 12, 2013

    thankyou so much!!!

  • Sarang
    June 12, 2013

    Thank you so much…Saved me 🙂

  • MUsa
    May 12, 2013

    Thanks a lot
    This is nice site for digital logic

  • Santosh Kumar Patel
    April 6, 2013

    Thank’s you so much it is good details for digital information. i will com back in your web sites.

  • ammar
    March 23, 2013

    Thanks a lot
    I hope if there is a suitable reference (student language not complex teacher language methods) for digital communication and for digital system design ??

  • varinder insa
    March 6, 2013

    its so so interesting & excellent

  • Martin
    February 14, 2013

    This is very interesting…

  • alireza
    February 14, 2013

    thanks

    • March 21, 2013

      Alireza
      I worked in the Postal Service, it had a large training section where we laearned to service electronic equipment. It was located in Norman, Oklament. At the University of Oklahoma. The last equipment I woked on was the Optical Cahriter Reader (OCR) the hardest logic I had to learn was the Master Slave J K Flipflop. I finnaly learned how it worked just before the test that was given every Friday. Well that was the only question I missed on the test. The instructor had a way to change just a little of something different.

  • pain
    December 30, 2012

    thank u 🙂

  • jatinder
    December 9, 2012

    good one and thanks dude for help me for this topic ………

  • Arunraj K
    December 4, 2012

    Thanks a lot. It will help to brush up my skills.

  • Arvind
    December 3, 2012

    Excellent!!!
    very helpful

  • Lakshya
    November 21, 2012

    Perfect !
    Now I think i can convert any flip flop to other !
    Thanks a lot !

  • baiduryakanti majumder
    November 7, 2012

    the figure in the conversion of jk to d is slightly incorrect …
    the last row in the conversion table should be corrected…i feel ….
    please comment if i am wrong…

  • farhaan
    September 26, 2012

    thank you very much.the explanations is quite simple and very easy to understand.please also post on registers.

  • LeDinhTan
    July 29, 2012

    Excellent! Thank you very much.

  • Sandip mangukiya
    July 23, 2012

    very good.explanation is quite simple and fundamentally stupedous

  • masoomeh
    July 21, 2012

    Excellent!
    Thank you.

  • Romel
    April 8, 2012

    Thank you very much john. Much needed topics!!

  • Rakesh
    March 3, 2012

    you worked really hard Mr. john. You concentrated upon a very useful topic.

    • poki
      July 29, 2013

      Excellent!
      Thank you so much!

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