Identify the monostable type A one-shot that begins an output pulse on a trigger edge and restarts (extends) the internal pulse timing if another trigger arrives before completion is called ________.

Difficulty: Easy

Correct Answer: retriggerable

Explanation:


Introduction / Context:
Monostable multivibrators (one-shots) generate a single output pulse in response to a trigger. Their behavior upon receiving additional triggers during the active pulse is the key distinction between retriggerable and non-retriggerable types.



Given Data / Assumptions:

  • A trigger edge starts the timing cycle.
  • Another trigger may occur before the pulse ends.
  • We must classify whether the device ignores or extends based on that second trigger.


Concept / Approach:
A retriggerable one-shot restarts or extends the pulse width each time a valid trigger is applied during the current pulse, effectively lengthening the total output duration. A non-retriggerable one-shot ignores additional triggers until it times out.



Step-by-Step Solution:

Define retriggerable behavior: new trigger restarts timing.Define non-retriggerable behavior: extra triggers are ignored.Match the described behavior (restart/extend) to “retriggerable.”Select the correct term.


Verification / Alternative check:
Review timing diagrams for datasheets like 74HC123 (retriggerable) versus 74HC121 (non-retriggerable).



Why Other Options Are Wrong:
“non-retriggerable” does not extend the pulse. “high-level triggered” and “edge-triggered” describe trigger sensitivity, not the retrigger behavior.



Common Pitfalls:
Confusing input triggering mode with retrigger capability; failing to account for minimum re-trigger interval and input conditioning.



Final Answer:
retriggerable

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