Retriggerable monostable multivibrator — identify what is NOT an inherent characteristic. Select the option that does not generally define retriggerable monostables across families.

Digital Electronics Multivibrators and 555 Timer Difficulty: Medium
Choose an option
  • A
    It is a dual multivibrator.
  • B
    It has an active-HIGH reset, which terminates all timing functions.
  • C
    It has no internal timing resistor.
  • D
    none of the above
  • E
    It extends the pulse if retriggered before timeout.

Answer

Correct Answer: It is a dual multivibrator.

Explanation

Introduction / Context:This item checks whether you can distinguish universal characteristics of retriggerable monostables from package- or family-specific features. The focus is on traits that are always true vs traits that may be true only for particular ICs.

Given Data / Assumptions:

  • We consider behavior and construction across common logic families (TTL/CMOS).
  • Terms like "dual" can describe a package option, not a fundamental property.

Concept / Approach:Retriggerability describes timing behavior: new triggers extend the active pulse. Whether an IC is "dual" (two monostables per package) or uses a particular reset polarity varies by part number and family. External timing components are also typical and not unique to retriggerable devices.

Step-by-Step Reasoning:

Identify core behavior: retriggering extends the output pulse.Check packaging: "dual" refers to two one-shots in one IC (e.g., certain 74x123 variants), not an inherent property.Reset polarity and internal components vary by manufacturer and subfamily.

Verification / Alternative check:Some retriggerable parts are single (one per package), others are dual. Therefore "dual" is not universally characteristic.

Why Other Options Are Wrong:

  • Active-HIGH reset: many parts provide a reset; polarity can vary, but a reset that halts timing is characteristic behavior broadly.
  • No internal timing resistor: timing typically uses external R and C in both retriggerable and non-retriggerable families.
  • Extends the pulse if retriggered: this is the very definition of retriggerable behavior.
  • none of the above: incorrect because at least one option (dual) is not inherent.

Common Pitfalls:

  • Assuming a datasheet feature of a specific IC is universal to all retriggerables.

Final Answer:It is a dual multivibrator.

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