The M54/74HC423/423A are high speed CMOS MONOSTABLE multivibrators fabricated with silicon gate C2MOS technology. They achieve the high speed operation similar to equivalent LSTTL while maintaining the CMOS low power dissipation. There are two trigger inputs, A INPUT (negative edge) and B INPUT (positive edge). These inputs are valid for rising/falling signals, (tr – tf – 1 sec). After triggering the output maintains the MONOSTABLE state for the time period determined by the external resistor Rx and capacitor Cx. Two different pulse width constant are available: K ≅ 0.46 for HC423 K ≅ 1 for HC423A. Taking CLR low breaks this MONOSTABLE STATE. If the next trigger pulse occurs during the MONOSTABLEp
The M54HC423/423A and M74HC423/423A are high‑speed CMOS dual retriggerable monostable multivibrators with two trigger inputs (A and B) and a direct reset input. They offer low power dissipation, high noise immunity and symmetrical output impedance, making them suitable for timing and pulse‑width applications.
The document lists functional descriptions, pin assignments, absolute maximum ratings, recommended operating conditions, DC and AC electrical characteristics, output pulse‑width curves, and mechanical dimensions. It also includes typical propagation delay (25 ns at 5 V), standby and active supply currents, and output drive capabilities.
| Typical propagation delay (tpp) | 25 ns at Vcc = 5 V |
|---|---|
| Active supply current (Ico) | 700 pA max at Vcc = 5 V |
| Low‑level output current | 4 mA (minimum) |
The device triggers when A is low and B has a falling edge, or when B is high and A has a rising edge, or when A is low, B is high and C1 has a rising edge.
The low‑level output current is specified as 4 mA (minimum rating).