Each multivibrator of the LS221 features a negative-transitiontriggered input and a positive-transition-triggered input either of which can be used as an inhibit input.
Pulse triggering occurs at a voltage level and is not related to the transition time of the input pulse. Schmitt-trigger input circuitry for B input allows jitter-free triggering for inputs as slow as 1 volt/second, providing the circuit with excellent noise immunity. A high immunity to VCC noise is also provided by internal latching circuitry.

• SN74LS221 is a Dual Highly Stable One-Shot
• Overriding Clear Terminates Output Pulse
• Pin Out is Identical to SN74LS123