Nonretriggerable

Nonretriggerable refers to a type of pulse-generating circuit or device, such as a monostable multivibrator, in which a trigger input produces a single output pulse of fixed duration. Once the pulse begins, additional triggers received during the active interval do not restart or extend the pulse. After the programmed duration elapses, the output returns to its quiescent state and the device is ready to respond to a new trigger.

This behavior contrasts with retriggerable devices, where a new trigger during the output pulse can extend or restart the timing, altering the pulse width. Nonretriggerable designs prioritize a predictable, unextendable pulse, which can simplify timing analysis and gating in certain applications.

Operation typically involves a trigger edge that sets the output high for a predetermined time, determined by external components or internal settings. Triggers during the timing interval are ignored or discarded, depending on the specific implementation. The timing accuracy and stability depend on device characteristics, including input thresholds, power supply, temperature, and the tolerances of external timing components.

Applications for nonretriggerable circuits include debouncing mechanical switches, pulse-stretching for single-event signaling, and gating or conditioning signals where a fixed-width pulse is required regardless of subsequent triggers during the pulse. Designers must consider the possibility of missed triggers if multiple events occur in rapid succession and ensure appropriate timing margins for the intended system.

See also: monostable multivibrator, retriggerable, one-shot, pulse-width, debounce.