MM54HC221A/MM74HC221A
Dual Non-Retriggerable Monostable Multivibrator
General Description
The MM54/74HC221A 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 'HC221A can be
triggered on the positive transition of the clear while A is
held low and B is held high.
The 'HC221A 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: 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.