Flip-Flop Concepts — Master–Slave J–K Behavior A master–slave J–K flip-flop is sometimes described as a pulse-triggered or level-triggered device. The statement claims: “input data is read during the entire time the clock pulse is at a LOW level.” State whether this statement is true or false, considering conventional master–slave operation.

Difficulty: Easy

Correct Answer: False

Explanation:


Introduction / Context:
A classic master–slave J–K flip-flop consists of two latches clocked on opposite phases. The “master” is enabled during one clock level, while the “slave” is enabled during the opposite level. Overall behavior appears edge-triggered because the slave transfers the master state only when the clock transitions. Understanding which clock level is sampled avoids timing mistakes.



Given Data / Assumptions:

  • Device: master–slave J–K flip-flop built from two gated latches.
  • Conventional design: if the device is labeled as positive-edge triggered, the master is transparent while the clock is HIGH, not LOW.
  • The statement asserts that sampling happens the entire time the clock is LOW.


Concept / Approach:
In a master–slave arrangement, one latch is transparent while the clock is at its active level and the other is opaque, then roles swap on the opposite level. Hence, for a positive-edge equivalent device, the master reads inputs during the HIGH level. The slave updates the output when the clock goes LOW, producing an effective edge-triggered transfer.



Step-by-Step Solution:
Identify the active sampling window: for positive-edge behavior, inputs affect the master while CLK is HIGH.Determine when outputs update: the slave becomes transparent when CLK goes LOW, passing the master state to the output.Compare with the claim: the statement says inputs are read during the entire LOW level, which is not the general case.Conclude the statement is incorrect.



Verification / Alternative check:
Timing diagrams show J and K gating the master while CLK is HIGH. When CLK falls, the slave latches the master state, yielding behavior indistinguishable from edge triggering.



Why Other Options Are Wrong:

  • True: Does not match typical master–slave timing.
  • Only true for asynchronous inputs: Asynchronous inputs (preset/clear) bypass the clock and are unrelated.
  • True only for T mode: T toggling derives from J = K = 1 but does not change which level is sampled.


Common Pitfalls:
Assuming the slave sampling window equals the input sampling window; confusing level-sensitive internal latches with the overall edge-triggered behavior.


Final Answer:
False

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