Jk Flip Flop Truth Table


What is JK flip-flop and its truth table?

What is JK Flip-Flop truth table? In the JK Flip-Flop truth table, when both inputs of the JK Flip-Flop are set to 1 and the clock input is also set to ‘High,’ the circuit is toggled from the SET to the RESET state. When both of its inputs are set to 1, the JK flip flop functions as a T-type toggle flip flop.

What is the JK flip-flop method?

What is JK Flip-Flop? – It is one kind of sequential logic circuit which stores binary information in bitwise manner. It consists of two inputs and two outputs. Inputs are Set(J) & Reset(K) and their corresponding outputs are Q and Q’. JK flipflop has two modes of operation which are synchronous mode and asynchronous mode. Jk Flip Flop Truth Table The JK flip flop diagram above represents the basic structure which consists of Clock (CLK), Clear (CLR), and Preset (PR). Below is the circuit diagram of JK Flip Flop. Two 3-input NAND gates are used in place of the original two 2-input AND gates. The outputs at Q and Q’ are coupled to each gate’s third input. Jk Flip Flop Truth Table In a circuit “set”, the bottom NAND gate interrupts the J input coming from the “0” position of Q’. In the “RESET” state, the top NAND gate interrupts the K input coming from the 0 positions of Q. We can use Q and Q’ to control the input because they are always different. The flip flop is toggled according to the truth table when both inputs “J” and “K” are set to 1.

What is the JK flip-flop characteristic table?

Construction of JK Flip-Flop Excitation Table – The JK Flip-Flop excitation table is derived from the JK flip-flop truth table information. The inputs are K = 0 or 1 and J = 0 from the truth table for the values of the current state and the next state, Q n = 0 and Q n+1 = 0 (marked in the first and third rows with yellow colour). The inputs are J = 1, K = 1 or J = 1, K = 0, and the state transition from the current state Q n = 0 to the next state Q n+1 = 1 occurs (indicated in the fifth and seventh row with pink colour). As a result, the data Q n = 0, Q n+1 = 1, J = 1, and K = X are entered into the excitation table.

The inputs are J = 0, K = 1 or J = 1, K = 1 for the transition from state 1 to state 0. (indicated in the fourth and eighth row with green colour). Therefore, J = X and K = 1 are the necessary inputs for this transition because J can be either 0 or 1. The J input can be 0 or 1, but the K input stays at 0 for the state transition from Q n = 1 to Q n+1 = 1.

(indicated in the second and sixth row with blue colour). The excitation inputs required for this transition are J = X and K = 0.

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What is true about the JK flip-flop?

A J-K flip-flop is nothing more than an S-R flip-flop with an added layer of feedback. This feedback selectively enables one of the two set/reset inputs so that they cannot both carry an active signal to the multivibrator circuit, thus eliminating the invalid condition.

Why is JK flip flop stable?

JK Flip-flop: – The name JK flip-flop is termed from the inventor Jack Kilby from texas instruments. Due to its versatility they are available as IC packages. The major applications of JK flip-flop are Shift registers, storage registers, counters and control circuits.

  1. Inspite of the simple wiring of D type flip-flop, JK flip-flop has a toggling nature.
  2. This has been an added advantage.
  3. Hence they are mostly used in counters and PWM generation, etc.
  4. Here we are using NAND gates for demonstrating the JK flip flop Whenever the clock signal is LOW, the input is never going to affect the output state,

The clock has to be high for the inputs to get active. Thus, JK flip-flop is a controlled Bi-stable latch where the clock signal is the control signal. Thus, the output has two stable states based on the inputs which have been discussed below. Truth table of JK Flip Flop:

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X LOW X X 0 1
HIGH HIGH 0 0 No Change
HIGH HIGH 0 1 0 1
HIGH HIGH 1 0 1 0
HIGH HIGH 1 1 Toggle
LOW HIGH X X No Change

The J (Jack) and K (Kilby) are the input states for the JK flip-flop. The Q and Q’ represents the output states of the flip-flop. According to the table, based on the inputs, the output changes its state. But, the important thing to consider is all these can occur only in the presence of the clock signal. Thus, comparing the three input and two input NAND gate truth table and applying the inputs as given in JK flip-flop truth table the output can be analysed. Analysing the above assembly as a two stage structure considering previous state (Q’) to be 0 When J = 1, K = 0 and CLOCK = HIGH Output: Q = 1, Q’ = 0. Working is correct. RESET: The RESET pin has to be active HIGH. All the pins will become inactive upon LOW at RESET pin. Hence, this pin always pulled up and can be pulled down only when needed. IC Package:

Q True Output
Q’ Compliment Output
CLOCK Clock Input
J Data input 1
K Data input 2
RESET Direct RESET (Low activated)
GND Ground
V CC Supply voltage

The IC used is MC74HC73A (Dual JK-type flip-flop with RESET). It is a 14 pin package which contains 2 individual JK flip-flop inside. Above is the pin diagram and the corresponding description of the pins.

Why is JK flip flop universal?

JK Flip Flop is a flip flop which consists of a few logic gates in front of a D-flip flop. A JK flip-flop is also called a universal flip-flop because it can be configured to work as an SR flip-flop, D flip-flop or T flip-flop.

Is JK flip flop positive or negative?

Description – The J-K Flip-Flop block models a negative-edge-triggered J-K flip-flop. The J-K flip-flop block has three inputs, J, K, and CLK, On the negative (falling) edge of the clock signal ( CLK ), the J-K Flip-Flop block outputs Q and its complement, !Q, according to the following truth table.

J K Q n !Q n
Q n-1 !Q n-1
1 1
1 1
1 1 !Q n-1 Q n-1

When J is 1 and K is 0, the flip-flop goes to the set state ( Q n is 1). When J is 0 and K is 1, the flip-flop goes to the reset state ( Q n is 0). When both J and K are 0, the flip-flop stays in the previous state ( Q n is Q n-1 ). When both J and K are 1, the flip-flop toggles ( Q n is the complement of Q n-1 ).

What is flip flop algorithm?

Flip-flop (programming) – Wikipedia For other uses, see, In, a flip-flop is a seldom-used syntactic construct which allows a boolean to flip from false to true when a first condition is met and then back to false when a second condition is met. The syntax is available in the programming languages and,

What are the 4 modes of the JK flip flops?

Due to this additional clocked input, a JK flip-flop has four possible input combinations, ‘logic 1’, ‘logic 0’, ‘no change’ and ‘toggle’.

What is JK flip flop timing diagram?

JK Flip Flop Timing Diagram This is known as a timing diagram for a JK flip flop. In addition to the basic input-output pins shown in Figure 1, J K flip-flops can also have special inputs like clear (CLR) and preset (PR) (Figure 4). These can be used to bring the flip-flop to a definite state from its current state.

What are flip-flop properties?

An animated interactive SR latch ( R1, R2 = 1 kΩ; R3, R4 = 10 kΩ). In electronics, flip-flops and latches are circuits that have two stable states that can store state information – a bistable multivibrator, The circuit can be made to change state by signals applied to one or more control inputs and will output its state (often along with its logical complement too).

  1. It is the basic storage element in sequential logic,
  2. Flip-flops and latches are fundamental building blocks of digital electronics systems used in computers, communications, and many other types of systems.
  3. Flip-flops and latches are used as data storage elements to store a single bit (binary digit) of data; one of its two states represents a “one” and the other represents a “zero”.

Such data storage can be used for storage of state, and such a circuit is described as sequential logic in electronics. When used in a finite-state machine, the output and next state depend not only on its current input, but also on its current state (and hence, previous inputs).

It can also be used for counting of pulses, and for synchronizing variably-timed input signals to some reference timing signal. The term flip-flop has historically referred generically to both level-triggered (asynchronous, transparent, or opaque) and edge-triggered ( synchronous, or clocked ) circuits that store a single bit of data using gates,

Modern authors reserve the term flip-flop exclusively for edge-triggered storage elements and latches for level-triggered ones. The terms “edge-triggered”, and “level-triggered” may be used to avoid ambiguity. When a level-triggered latch is enabled it becomes transparent, but an edge-triggered flip-flop’s output only changes on a clock edge (either positive going or negative going).

How is a JK flip flop made to toggle?

Solution: – A J-K flip flop happens to be toggled when both input J and K are high or true or set at 1. When J and K are tied together or set at 1 then the present state is equal to the previous state and gets complimented that 0 becomes 1 or 1 becomes 0. Therefore, a J-K flip flop made to toggle_? is J=1,K=1, Hence, option (D) is the correct answer.

Why is JK flip flop used over SR?

The advantage of a JK flip-flop is that it removes the not allowed condition present in the SR flip-flop for an input of SR=11. It has two NAND gates and the input of both the gates is connected to different outputs.

What are the limitations of J-K flip-flop?

JK Flip Flop The JK Flip Flop is the most widely used flip flop. It is considered to be a universal flip-flop circuit. The sequential operation of the JK Flip Flop is the same as for the RS flip-flop with the same SET and RESET input. The difference is that the JK Flip Flop does not the invalid input states of the RS Latch (when S and R are both 1).

  • The basic symbol of the JK Flip Flop is shown below:
  • The basic NAND gate RS flip-flop suffers from two main problems.
  • Firstly, the condition when S = 0 and R = 0 should be avoided.
  • Secondly, if the state of S or R changes its state while the input which is enabled is high, the correct latching action does not occur.

Thus to overcome these two problems of the RS Flip-Flop, the JK Flip Flop was designed. The JK Flip Flop is basically a gated RS flip flop with the addition of the clock input circuitry. When both the inputs S and R are equal to logic “1”, the invalid condition takes place.

  1. The circuit diagram of the JK Flip Flop is shown in the figure below:
  2. The S and R inputs of the RS bistable have been replaced by the two inputs called the J and K input respectively.

Here J = S and K = R. The two-input AND gates of the RS flip-flop is replaced by the two 3 inputs NAND gates with the third input of each gate connected to the outputs at Q and Ǭ. This cross-coupling of the RS Flip-Flop is used to produce toggle action.

As the two inputs are interlocked. If the circuit is in the “SET” condition, the J input is inhibited by the status 0 of Q through the lower NAND gate. Similarly, the input K is inhibited by 0 status of Q through the upper NAND gate in the “RESET” condition. When both J and K are at logic “1”, the JK Flip Flop toggle.

The Truth Table of the JK Flip Flop is shown below.

J K Q Ǭ Description
Same as for the RS Latch Memory No Change
1 1 Reset Q >> 0
1 1
1 1 Set Q >> 1
1 1
Toggle 1 1 1 Toggle
1 1 1

JK Flip Flop is similar to RS flip flop with the feedback which enables only one of its input terminals. It eliminates the invalid condition which arises in the RS flip flop and put the input terminal either to set or reset condition one at a time. When both the J and K inputs are at logic “1” at the same time and the clock input is pulsed HIGH, the circuit toggle from its SET state to a RESET or visa versa.

When both the terminals are HIGH the JK flip-flop acts as a T type toggle flip-flop. JK flip-flop has a drawback of timing problem known as “RACE”. The condition of RACE arises if the output Q changes its state before the timing pulse of the clock input has time to go in OFF state. The timing pulse period (T) should be kept as short as possible to avoid the problem of timing.

This condition is not possible always thus a much-improved flip-flop named Master Salve JK Flip Flop was developed. This eliminates all the timing problems by using two RS flip-flop connected in series. One is for the “MASTER ” circuit, which triggers on the leading edge of the clock pulse.

Is J-K flip-flop synchronous?

Simulation Results from Simscape Logging – The plots below show the inputs and outputs for the synchronous J-K flip-flop. Both inputs to the flip-flop are set high so its output state toggles each time the clock signal goes low.

Is a J-K flip-flop versatile?

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,traditionally labeled J and K. If J and K are different then the output Q takes the value of J at the next clock edge.

Which flip flop is most important?

D Flip Flop In SR NAND Gate Bistable circuit, the undefined input condition of SET = “0” and RESET = “0” is forbidden. It is the drawback of the SR flip flop. This state:

Override the feedback latching action. Force both outputs to be 1. Lose the control by the input, which first goes to 1, and the other input remains “0” by which the resulting state of the latch is controlled.

We need an inverter to prevent this from happening. We connect the inverter between the Set and Reset inputs for producing another type of flip flop circuit called, Delay flip flop, D-type Bistable, D-type flip flop. The D flip flop is the most important flip flop from other clocked types.

  1. It ensures that at the same time, both the inputs, i.e., S and R, are never equal to 1.
  2. The Delay flip-flop is designed using a gated with an inverter connected between the inputs allowing for a single input D(Data).
  3. This single data input, which is labeled as “D” used in place of the “Set” input and for the complementary “Reset” input, the inverter is used.

Thus, the level-sensitive D-type or D flip flop is constructed from a level-sensitive SR flip flop. So, here S=D and R= ~D(complement of D)

Why is flip flop preferred?

Which is better latches or flip flop Generally Flip-Flops are used, but Latches are also usefull in some situations. Flip-Flops are easiest to use with state machines. Flip-Flops only change on the rising (or falling) edge of the clock. Their data input should not change during a timeframe near that clock edge – this timeframe is defined by the ‘setup time’ and the ‘hold time’.

Latches are not triggered by the clock edge, but they are “open” or “closed” depending on the gate (or enable) signal. While they are open the standard output (generally Q) will follow the data input. To have a deterministic behavior, they also require that the data input is stable during a given time frame near the “falling edge” of the enable signal (if the latch is open when the enable signal is high).

The Flip-Flop and Latch outputs define states of the state machine. In case of Flip-Flops, the new states are stable until the next clock edge. When the Flip-Flop output changes, this new output is presented to the “next” Flip-Flop (after passing through combinational logic if any).

  1. This “next” Flip-Flop will ignore the change because the clock edge happened before the data input change.
  2. Therefore, the system is stable just after the clock edge.
  3. With Latches, when the gates are opened, the output also changes (the same as with Flip-Flops), but the next latch (using the same enable signal) will propagate the data input change immediately (because the next latch is still open).

This output change may have an impact on the output of the first Latch, which changes its output again, in which case the second Latch also changes its output. This can result in an unstable system. But Latches also have advantages over Flip-Flops:

  • They are smaller;
  • They do not require steep clock edges (resulting in lower EMC emissions).

And there are techniques to use them:

  1. Use the Latches in a Master-Slave Flip-Flop
  2. Design the state-machine so that there is only one bit change at a time.

What is the difference between JK and T flip flops?

4) T flip flop – T flip-flop is known as toggle flip-flop. The T flip-flop is modification of the J-K flip-flop. Both the JK inputs of the JK flip – flop are held at logic 1 and the clock signal continuous to change as shown in table below. Figure-7:Circuit diagram of T flip flop Jk Flip Flop Truth Table Figure-8:Characteristics table of T flip flop : Virtual Labs

What is JK and SR flip-flop?

What is JK Flip-Flop? – JK flip flop is also a 1-bit storage device having two inputs similar to SR flip flop, but it has inputs denoted by J and K instead of S and R. It has two outputs viz. Q (normal output) and Q’ (inverted output). The clock signal is used for synchronization of the circuit. The block diagram of the JK flip flop is shown in Figure-2 below. Jk Flip Flop Truth Table The operation of the JK flip flop can be understood with the help of its truth table which is given below −

Inputs Output
J K Q n+1
Q n
1 1
1 1 Toggle

The characteristic equation of the JK flip flop is given by, $$Q_ =JQ_ ‘+K’Q_ $$ After discussing about the basics of SR flip flop and JK flip flop. Let us now discuss the conversion of SR flip flop into JK flip flop.

What is JK and D flip-flop?

Conversion of J-K Flip-Flop into D Flip-Flop Prerequisite – 1. JK Flip-Flop: JK Flip-Flip is basically a gated SR flip-flop which has an additional input that is clock input. It prevents the invalid output that may be obtained when both the inputs are 1.2.

Step-1: We construct the characteristic table of D flip-flop and excitation table of JK flip-flop. Jk Flip Flop Truth Table Step-2: Using the K-map we find the boolean expression of J and K in terms of D. Jk Flip Flop Truth Table J = D K = D’ Step-3: We construct the circuit diagram of the conversion of JK flip-flop into D flip-flop.

Last Updated : 22 Apr, 2020 Like Article Save Article

: Conversion of J-K Flip-Flop into D Flip-Flop

What is the difference between JK and SR flip-flop truth table?

In J-K flip flop when both inputs are HIGH, the output toggles i.e. it changes from high to low and low to high periodically when both the inputs are 1. For an SR flip flop, however, when both the inputs are HIGH, we encounter an invalid state, which is not present for a JK flip flop.

What is the truth table?

A truth table provides a method for mapping out the possible truth values in an expression and to determine their outcomes. The table includes a column for each variable in the expression and a row for each possible combination of truth values. It also includes a column that shows the outcome of each set of values.