Monostable Pulse Timing: Trigger Events and the Output Pulse Width Are Separate

Keep the pulse definition complete

TI describes a monostable device with retriggerable/resettable operation and an external timing relationship. Retrigger behavior is part of its stated operation. Primary reference: monostable description.

The trigger is an input event; the output pulse is a resulting timed condition. They need not have the same duration. A pulse-width label also needs to say what happens when another valid trigger arrives before the existing pulse has ended.

A hypothetical retrigger comparison

Assume an idealized one-shot interval of 20 ms. A trigger at 0 ms would produce a pulse ending at 20 ms if nothing else occurs. With a fictional retriggerable model that restarts its complete interval, another valid trigger at 12 ms moves the end to 32 ms.

In a different explicitly non-retriggerable model that ignores triggers while active, the end remains 20 ms. The same input event sequence now produces different output timing. These cases introduce no particular chip connection, R–C value or actual machine pulse requirement.

Prepare a timing diagram

Place trigger times, output state, preset interval, reset events and the exact retrigger rule on one time axis. Identify which edge is accepted by the intended device.

Ask how the actual documented behavior handles active-period triggers and power-up. A useful proposal preserves that behavior rather than promising a fixed pulse duration while leaving its repeated-trigger condition unexplained. The worksheet is a logic review, not a board modification instruction.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• Primary reference: monostable description