MM54HC123A/MM74HC123A Dual Retriggerable Monostable Multivibrator General Description The MM54/74HC123A high speed monostable multivibrators (one shots) utilize advanced silicon-gate CMOS technology. They feature speeds comparable to low power Schottky TTL circuitry while retaining the low power and high noise immunity characteristic of CMOS circuits. Each multivibrator features both a negative, A, and a positive, B, transition triggered input, either of which can be used as an inhibit input. Also included is a clear input that when taken low resets the one shot. The 'HC123 can be triggered on the positive transition of the clear while A is held low and B is held high. The 'HC123A is retriggerable. That is it may be triggered repeatedly while their outputs are generating a pulse and the pulse will be extended. Pulse width stability over a wide range of temperature and supply is achieved using linear CMOS techniques. The output pulse equation is simply: PWe(REXT) (CEXT); where PW is in seconds, R is in ohms, and C is in farads. All inputs are protected from damage due to static discharge by diodes to VCC and ground. Features Y Typical propagation delay: 25 ns Y Wide power supply range: 2V±6V Y Low quiescent current: 80 mA maximum (74HC Series) Y Low input current: 1 mA maximum Y Fanout of 10 LS-TTL loads Y Simple pulse width formula T e RC Y Wide pulse range: 400 ns to % (typ) Y Part to part variation: g5% (typ) Y Schmitt Trigger A & B inputs enable infinite signal input rise and fall times.