T flip-flopsJK flip flop truth tableJk flip flop waveformjk flip flop原理Toggle jk flip flopJ-K flip flop counter

J-K Flip-Flop - Hyperphysics

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The J-K flip-flop is the most versatile of the basic flip-flops. It has the input- following character of the clocked D flip-flop but has two inputs ... J-KFlip-Flop TheJ-Kflip-flopisthemostversatile ofthebasicflip-flops.Ithastheinput- followingcharacteroftheclocked Dflip-flopbuthastwoinputs,traditionally labeledJandK.IfJandKaredifferent thentheoutputQtakesthevalueofJat thenextclockedge.TheinputsarelabeledJandKinhonoroftheinventorofthedevice,JackKilby. ExamineStructureApplications IfJandKarebothlow thennochangeoccurs.IfJandKarebothhigh attheclockedgethentheoutputwilltogglefromonestatetotheother.Itcanperformthefunctionsoftheset/resetflip-flopandhastheadvantagethattherearenoambiguousstates.ItcanalsoactasaTflip-floptoaccomplishtogglingactionifJandKaretiedtogether.Thistoggleapplicationfindsextensiveuseinbinarycounters. Flip-Flops IndexElectronicsconceptsDigitalcircuitsSequentialOperationsJ-KFlip-FlopApplications  HyperPhysics*****ElectricityandmagnetismRNave GoBack J-KFlip-FlopStructure AsimplifiedversionoftheversatileJ-Kflip-flop.NotethattheoutputsfeedbacktotheenablingNANDgates.ThisiswhatgivesthetogglingactionwhenJ=K=1. WhilethisimplementationoftheJ-Kflip-flopwithfourNANDgatesworksinprinciple,thereareproblemsthatarisewiththetiming.ThetimingpulsemustbeveryshortbecauseachangeinQbeforetheclockpulsegoesoffcandrivethecircuitintoanoscillationcalled"racing".ModernICsaresofastthatthissimpleversionoftheJ-Kflip-flopisnotpractical(weputonetogetherinthelabwithanavailable4-NANDchipanditwasveryunstableagainstracing). ThenextstepinmakinguseoftheversatileJ-Kflip-flopistousefouradditionalNANDgatestocreatetheMaster-SlaveJKFlipFlopwhichhastwogatedSRflipflopsusedaslatchesinawaythatsuppressesthe"racing". SwitchingExample Flip-Flops IndexElectronicsconceptsDigitalcircuitsElectronicsTutorialsallaboutcircuits  HyperPhysics*****ElectricityandmagnetismRNave GoBack SwitchingExample:Master-SlaveJ-KFlip-Flop Thepositivegoingtransition(PGT)oftheclockenablestheswitchingoftheoutputQ.The"enable"conditiondoesnotpersistthroughtheentirepositivephaseoftheclock.TheJ&Kinputsalonecannotcauseatransition,buttheirvaluesatthetimeofthePGTdeterminetheoutputaccordingtothetruthtable.ThisisanapplicationoftheversatileJ-Kflip-flop.Sincethis4-NANDversionoftheJ-Kflip-flopissubjecttothe"racing"problem,theMaster-SlaveJKFlipFlopwasdevelopedtoprovideamorestablecircuitwiththesamefunction. TheMaster-SlaveJKFlipFlophastwogatedSRflipflopsusedaslatchesinawaythatsuppressesthe"racing"or"racearound"behavior.AnotherwaytolookatthiscircuitisastwoJ-Kflip-flopstiedtogetherwiththeseconddrivenbyaninvertedclocksignal. Whentheclockmakesapositivetransitionthemastersectionistriggeredbuttheslavesectionisnotbecauseitsclockisinverted.Atahalfcycleoftheclock,onthedownwardtransition,theinvertedclockhasapositivetransitionandtriggerstheslavesection.ThefinaloutputQthentrackstheoutputofthemastersectionMafterahalfcycleoftheclock. Flip-Flops IndexElectronicsconceptsDigitalcircuitsReferenceTocciDigitalSystems,p170DigitalcircuitsElectronicsTutorialsallaboutcircuits  HyperPhysics*****ElectricityandmagnetismRNave GoBack J-KFlip-FlopDataTransfer InsynchronousdatatransferbetweentwoJ-Kflip-flops,atransfersignalontheclockinputcausestransferfromcellAtocellB.Thetransfersignalcouldbeappliedtoseveralsuchcellsinseriestocreateashiftregister. Inasynchronousdatatransfer,atransferpulsemaybeappliedatanytimetoforcethedataontotheasychronoussetandclearinputs,storingthedataregardlessofwhatishappeningontheotherinputs. Flip-Flops IndexElectronicsconceptsDigitalcircuitsDataTransferJ-KFlip-FlopApplicationsReferenceTocciDigitalSystems,Sec5-9,5-17  HyperPhysics*****ElectricityandmagnetismRNave GoBack J-KFlip-FlopInstabilityor"Racing" AsimplifiedversionoftheversatileJ-Kflip-flop.NotethattheoutputsfeedbacktotheenablingNANDgates.ThisiswhatgivesthetogglingactionwhenJ=K=1.Thetogglingmightbeadesiredbehavior,butgenerallyyouwouldlikeforthetimesoftogglingtobecontrolledbytheclockpulsesasenablerssothatyoucouldcontrolandpredicttheoutput. ForthisversionoftheJ-Kflip-flopundertheinputconditionsJ=K=1thetogglingwouldbeenabledanytimetheclockhasvalue1,andthetogglingratewouldbedeterminedbythepropagationdelayaroundthecircuit.Thevalueoftheoutputatanytimewouldnotbepredictablefromtheclockstate.Thisiscalled"racing"orthe"race-aroundcondition".Thisuncontrolledtogglingcanbesuppressedbyusingthemaster-slavearrangementwherethetransmissionoftheJvaluetotheoutputisdelayedbyhalfaclockcycleandnotimmediatelyfedbacktotheinputside. SwitchingExample Flip-Flops IndexElectronicsconceptsDigitalcircuitsDataTransferJ-KFlip-FlopApplicationsReferencesTocciDigitalSystems,Sec5-9,5-17ECETurorials/  HyperPhysics*****ElectricityandmagnetismRNave GoBack

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