The 74HC/HCT123 is a dual retriggerable monostable multivibrator with reset. It is a high-voltage, high-output-drive device with Schmitt trigger action on all inputs except the reset input.
The 74HC/HCT123 are high-speed Si-gate CMOS devices designed as dual retriggerable monostable multivibrators with reset functionality. They are specified in compliance with JEDEC standard no. 7A and are pin compatible with low power Schottky TTL (LSTTL). The output pulse width is controlled by external resistor and capacitor values, and the circuit can be retriggered for very long pulses up to a 100% duty factor.
| Device Type | Dual retriggerable monostable multivibrator with reset |
|---|---|
| Logic Family | High-speed Si-gate CMOS |
| TTL Compatibility | Pin compatible with LSTTL |
| Retrigger Capability | Up to 100% duty factor |
| Reset Function | Direct reset terminates output pulse |
| Input Action | Schmitt-trigger action |
The output pulse width is controlled by the selection of an external resistor (Rext) and capacitor (Cext).
Yes, the output pulse width may be extended by retriggering the gated active LOW-going edge input (nA) or the active HIGH-going edge input (nB).
An output delay can be terminated at any time by a LOW-going edge on input nRp, which also inhibits the triggering.
The '123' is identical to the '423' but can be triggered via the reset input.