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Question

In a J-K flip flop, when J = 1 and K = 1 then it will be considered as:

The correct answer is

toggle condition

J-K Flip-Flop Basics

A J-K flip-flop is a fundamental building block in digital electronics, categorized as a sequential logic circuit. It is an improved version of the SR flip-flop, designed to overcome the indeterminate state problem where the output becomes unpredictable when both set (S) and reset (R) inputs are simultaneously high (1). The J-K flip-flop achieves this by introducing a "toggle" feature, which makes it highly versatile for various digital applications like counters, registers, and memory units.

J-K Flip-Flop Operating Modes

The behavior of a J-K flip-flop is determined by the combination of its J and K inputs and the presence of a clock pulse. Unlike SR flip-flops, the J-K flip-flop provides a defined output for all input combinations. Here's a breakdown of its four primary operating modes:

J Input K Input Next State (\(Q_{n+1}\)) Condition/Mode
0 0 \(Q_n\) No Change / Hold Condition
0 1 0 Reset Condition
1 0 1 Set Condition
1 1 \(\overline{Q_n}\) Toggle Condition

J=1 and K=1: The Toggle Condition

When both the J input and the K input of a J-K flip-flop are set to 1 (\(J=1\), \(K=1\)), the flip-flop enters its unique toggle condition. In this mode, with each active transition of the clock pulse, the output \(Q\) will switch to its complementary state. This means if the current output \(Q_n\) was 0, the next output \(Q_{n+1}\) will become 1. Conversely, if \(Q_n\) was 1, then \(Q_{n+1}\) will become 0. This behavior is represented mathematically as \(Q_{n+1} = \overline{Q_n}\).

The term "toggle" perfectly describes this action, as the output "flips" or "toggles" between 0 and 1. This characteristic makes the J-K flip-flop particularly useful in frequency division and counter circuits, where a continuous flipping action is required.

Therefore, when \(J=1\) and \(K=1\), the J-K flip-flop will exhibit the toggle condition.

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Important Questions from Flip-Flop

  1. In D flip-flop, if D = 1, then the output of the D flip-flop is ______, but if D = 0, then the output of D flip-flop goes to ______ state.

  2. Which of the following statements about the T-type flip-flop is correct?

    I. If T = 1, Changes the state of the lining clock pulse.

    II. If T = 0, the state does not change. 

  3. For a JK Flip‐flop

    A. When J = 0, K = 1, Q n+1 = 0

    B. When J = 1, K = 1, Q n+1 = 1

    C. When J = 1, K = 1, Q n+1 =\(\rm \overline{Q_n}\)

    D. When J = 1, K = 0, Q n+1 = 1

    E. When J = 1, K = 0, Q n+1 = 0

    Choose the correct answer from the options given below:

  4. Which of the following pair is/are correct?

    I. Astable multivibrator - Flip Flop

    II. Bistable multivibrator - Free running

  5. Toggle condition is present in which of the following?

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