Edge-triggering polarity: A positive edge-triggered flip-flop changes state on a HIGH-to-LOW clock transition. Evaluate the statement.

Difficulty: Easy

Correct Answer: Incorrect

Explanation:


Introduction / Context:
Edge-triggered devices respond on a specific transition of the clock: positive (rising) or negative (falling). Understanding clock polarity is essential for timing design and multi-stage pipelines.



Given Data / Assumptions:

  • Positive edge-triggered means action on LOW-to-HIGH transition.
  • Negative edge-triggered means action on HIGH-to-LOW transition.
  • Clock-to-output delay follows the triggering edge.


Concept / Approach:
The statement claims a positive edge-triggered device reacts on a falling edge (HIGH-to-LOW), which contradicts the definition. Therefore, the statement must be judged incorrect.



Step-by-Step Solution:

Recall: Positive edge = rising edge = LOW-to-HIGH.Given statement: “changes on HIGH-to-LOW.” That is a falling edge.Thus, the statement mislabels the triggering edge.Conclusion: The statement is incorrect.


Verification / Alternative check:
Datasheets use a triangle or up-arrow symbol near the clock for positive edge; a down-arrow for negative edge. Rising edges are explicitly indicated as 0→1 transitions.



Why Other Options Are Wrong:

Correct: Would agree with the false claim; not acceptable.“True only for master–slave” or “with Schmitt clocks”: Edge polarity is independent of these details.


Common Pitfalls:
Confusing edge polarity; overlooking that duty cycle does not affect which edge triggers (only timing margins do).


Final Answer:
Incorrect

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