SN74LS221
AC CHARACTERISTICS
(V
CC
= 5.0 V, T
A
= 25°C)
Symbol
t
PLH
From
(Input)
A
B
A
t
PHL
t
PHL
t
PLH
B
Clear
Clear
To
(Output)
Q
Q
Q
Q
Q
Q
70
20
t
W(out)
( )
A or B
Q or Q
600
6.0
670
6.9
750
7.5
ms
Limits
Min
Typ
45
35
50
40
35
44
120
47
Max
70
ns
55
80
ns
65
55
65
150
70
ns
ns
ns
C
L
= 15 pF,
See Figure 1
C
ext
= 80 pF, R
ext
= 2.0
Ω
C
ext
= 0, R
ext
= 2.0 kΩ
C
ext
= 100 pF, R
ext
= 10 kΩ
C
ext
= 1.0
µF,
R
ext
= 10 kΩ
C
ext
= 80 pF R
ext
= 2.0
Ω
pF,
20
Unit
Test Conditions
AC SETUP REQUIREMENTS
(V
CC
= 5.0 V, T
A
= 25°C)
Limits
Symbol
Parameter
Rate of Rise or Fall of Input Pulse
dv/dt
Schmitt, B
Logic Input, A
Input Pulse Width
t
W
t
s
R
ext
C
ext
Clear-Inactive-State Setup Time
External Timing Resistance
External Timing Capacitance
Output Duty Cycle
RT = 2.0 kΩ
R
T
= MAX R
ext
50
90
%
A or B, t
W(in)
Clear, t
W
(clear)
40
40
15
1.4
0
100
1000
ns
kΩ
µF
ns
1.0
1.0
V/s
V/µs
Min
Typ
Max
Unit
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