HD74LS221 Datasheet, PDF (2/9 Pages) Hitachi Semiconductor – Dual Monostable Multivibrators

HD74LS221
Pin Arrangement
1A 1
1B 2
1CLR 3
1Q 4
2Q 5
2 Cext 6
2 Rext/Cext 7
GND 8
CLR
Q
Q
Q
Q
CLR
(Top view)
Function Table
Inputs
Clear
A
B
L
X
X
X
H
X
X
X
L
H
L
↑
H
↓
H
↑
L
H
Notes: H; high level, L; low level, X; irrelevant.
↓; Transition from high to low level.
↑; Transition from low to high level.
; one high-level pulse.
; one low-level pulse.
Block Diagram (1/2)
A
16 V_CC
15 _{1 Rext/Cext}
14 _{1 Cext}
13 _1Q
12 _2Q
11 _2CLR
10 _2B
9 2A
Outputs
Q
Q
L
H
L
H
L
H
Q
Q
B
Clear
Q
Q
Clear
Rev.3.00, Jul.15.2005, page 2 of 8