MM74HC221A

MM74HC221A Dual Non-Retriggerable Monostable Multivibrator September 1983 Revised February 1999 MM74HC221A Dual Non-Retriggerable Monostable Multivibrator General Description The MM74HC221A 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 MM74HC221A can be triggered on the positive transition of the clear while A is held LOW and B is held HIGH. The MM74HC221A is a non-retriggerable, and therefore cannot be retriggered until the output pulse times out. Pulse width stability over a wide range of temperature and supply is achieved using linear CMOS techniques. The output pulse equation is simply: PW = (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 s Typical propagation delay: 40 ns s Wide power supply range: 2V–6V s Low quiescent current: 80 µA maximum (74HC Series) s Low input current: 1 µA maximum s Fanout of 10 LS-TTL loads s Simple pulse width formula T = RC s Wide pulse range: 400 ns to ∞ (typ) s Part to part variation: ±5% (typ) s Sch...