Retriggerable one-shot timing in digital electronics: A monostable multivibrator (retriggerable one-shot) has nominal pulse width T = 10 ms. It is triggered at t = 0, and then a second valid trigger arrives 3 ms later (t = 3 ms) while the output is still active. What will be the total output pulse duration measured from t = 0, in milliseconds?

Introduction / Context:
Retriggerable one-shots (monostables) are timing circuits that extend their output pulse whenever a new valid trigger occurs before the existing timing interval has expired. This question checks your understanding of how the output width accumulates when a second trigger occurs during the active pulse window.

Given Data / Assumptions:

• Pulse width setting T = 10 ms.
• First trigger occurs at t = 0 ms.
• Second valid trigger occurs at t = 3 ms while output is still high.
• Monostable is retriggerable, meaning each new trigger restarts the timing window from that instant.

Concept / Approach:
In a retriggerable monostable, any trigger that arrives while the output is high resets the internal timing capacitor/threshold process so that the output remains high for a full additional interval T starting from the new trigger time. The output therefore stays high until (time of last trigger) + T.

Step-by-Step Solution:

Verification / Alternative check:
Draw a timeline and shade the high-level region. The first window would end at 10 ms, but the second trigger shifts the end to 13 ms. This matches standard timing diagrams from retriggerable one-shot IC datasheets (e.g., 74HC123 behavior).

Why Other Options Are Wrong:

• 7 or 3: These ignore retriggering or miscalculate duration.
• 10: True only for non-retriggerable (one-shot) or if no second trigger occurs.
• 9: Arithmetic error; not aligned with retriggered timing from 3 ms.

Common Pitfalls:
Confusing retriggerable with non-retriggerable devices; assuming the second trigger “overlaps” without extending; or measuring from the second trigger only and forgetting the total duration from t = 0 when asked for overall pulse length.

Final Answer:
13