The 74HC/HCT123 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A. The 74HC/HCT123 are dual retriggerable monostable multivibrators with output pulse width control by three methods. The basic pulse time is programmed by selection of an external resistor (REXT) and capacitor (CEXT). The external resistor and capacitor are normally connected as shown in Fig.6. Once triggered, the basic output pulse width may be extended by retriggering the gated active LOW-going edge input (nA) or the active HIGH-going edge input (A).
The Philips 74HC/HCT123 are high-speed Si-gate CMOS devices that function as dual retriggerable monostable multivibrators with reset. They are pin compatible with low power Schottky TTL (LSTTL) and feature Schmitt-trigger action on all inputs except the reset input. The output pulse width is controlled by external timing components, and the circuit can be retriggered for very long pulses up to a 100% duty factor.
| Propagation delay (nA, nB to nQ) | 26 ns (typical) |
|---|---|
| Output pulse width formula | tw = 0.45 x Rext x Cexr |
| Supply voltage range (HC) | -40 to +85 V |
Yes, the basic 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.