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.