MM74HC123A Dual Retriggerable Monostable Multivibrator
September 1983
Revised May 2001
MM74HC123A
Dual Retriggerable Monostable Multivibrator
General Description Features
The MM74HC123A high speed monostable multivibrators Typical propagation delay: 25 ns
(one shots) utilize advanced silicon-gate CMOS technol-
Wide power supply range: 2V6V
ogy. They feature speeds comparable to low power Schot-
Low quiescent current: 80 A maximum (74HC Series)
tky TTL circuitry while retaining the low power and high
Low input current: 1 A maximum
noise immunity characteristic of CMOS circuits.
Fanout of 10 LS-TTL loads
Each multivibrator features both a negative, A, and a posi-
Simple pulse width formula T = RC
tive, B, transition triggered input, either of which can be
used as an inhibit input. Also included is a clear input that
Wide pulse range: 400 ns to (typ)
when taken low resets the one shot. The MM74HC123A
Part to part variation: 5% (typ)
can be triggered on the positive transition of the clear while
Schmitt Trigger A & B inputs allow rise and fall times to
A is held LOW and B is held HIGH.
be as slow as one second
The MM74HC123A is retriggerable. That is it may be trig-
gered 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 out-
put pulse equation is simply: PW = (R ) (C ); where
EXT EXT
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 V and ground.
CC
Ordering Code:
Order Number Package Number Package Description
MM74HC123AM M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow
MM74HC123ASJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
MM74HC123AMTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
MM74HC123AN N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter X to the ordering code.
Timing Component
Connection Diagram
Note: Pin 6 and Pin 14 must be hard-wired to GND.
Top View
2001 Fairchild Semiconductor Corporation DS005206 www.fairchildsemi.comTruth Table
Inputs Outputs
Clear AB Q Q
LX X L H
XH X L H
XX L L H
HL
H H
LH
H = HIGH Level
L = LOW Level
= Transition from LOW-to-HIGH
= Transition from HIGH-to-LOW
= One HIGH Level Pulse
= One LOW Level Pulse
X = Irrelevant
Logic Diagram
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MM74HC123A