November 1987
Revised May 2002
MM74C221
Dual Monostable Multivibrator
General Description
The MM74C221 dual monostable multivibrator is a mono-
lithic complementary MOS integrated circuit. Each multivi-
brator features a negative-transition-triggered input and a
positive-transition-triggered input, either of which can be
used as an inhibit input, and a clear input.
Once fired, the output pulses are independent of further
transitions of the A and B inputs and are a function of the
external timing components CEXT and REXT. The pulse
width is stable over a wide range of temperature and VCC.
Pulse stability will be limited by the accuracy of external
timing components. The pulse width is approximately
defined by the relationship tW(OUT) ≈ CEXT REXT. For fur-
ther information and applications, see AN-138.
Features
s Wide supply voltage range: 4.5V to 15V
s Guaranteed noise margin: 1.0V
s High noise immunity: 0.45 VCC (typ.)
s Low power TTL compatibility: fan out of 2 driving 74L
Ordering Code:
Order Number Package Number
Package Description
74MMC221N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Connection Diagrams
Timing Component
Truth Table
Inputs
Clear
A
B
L
X
X
X
H
X
X
X
L
H
L
↑
H
↓
H
H = HIGH Level
L = LOW Level
X= Irrelevant
↑ = Transition from LOW-to-HIGH
↓ = Transition from HIGH-to-LOW
= One HIGH Level Pulse
= One LOW Level Pulse
Outputs
Q
Q
L
H
L
H
L H
Top View
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