Retriggerable one-shot behavior during an active output pulse What happens if a retriggerable monostable is triggered again before the current output pulse ends?

Introduction / Context:
Retriggerable monostable multivibrators (retriggerable one-shots) produce a single pulse of defined width after a trigger. Unlike non-retriggerable types, if another valid trigger arrives while the output is still high, they can modify the timing of the pulse. This question checks that key distinction.

Given Data / Assumptions:

• Device is explicitly retriggerable.
• A subsequent trigger occurs before the current pulse returns low.
• Pulse width is determined by an internal or external timing network (R*C type).

Concept / Approach:

In retriggerable one-shots, a new trigger restarts the timing cycle from that instant. The output stays high and the measured width extends relative to the most recent trigger, effectively lengthening the total duration.

Step-by-Step Solution:

Verification / Alternative check:

Datasheets for retriggerable devices (e.g., 74123 types) show timing diagrams where each retrigger adds a new interval, extending the total high period as long as triggers keep arriving within T.

Why Other Options Are Wrong:

“time out the original pulse”: contradicts the retriggerable definition (that would describe non-retriggerable operation).
“have no effect”: incorrect; retriggering explicitly alters pulse duration.
“double the original pulse width”: only true if exactly one retrigger occurs at the pulse midpoint; in general, the width extends by a full interval from the last trigger, not necessarily doubling.

Common Pitfalls:

Confusing retriggerable with non-retriggerable operation; assuming fixed total pulse regardless of additional triggers; neglecting minimum trigger width/threshold constraints.

Final Answer:

extend the pulse to this trigger width