HD74LS221 查看數據表（PDF） - Renesas Electronics
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HD74LS221 Datasheet PDF : 9 Pages
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HD74LS221
Switching Characteristics
(VCC = 5 V, Ta = 25°C)
Item
Symbol Inputs Outputs min.
typ.
max.
Unit
Condition
A
tPLH
B
Q
—
45
70
ns
Q
—
35
55
Propagation
A
delay time
tPHL
B
Q
Q
—
—
50
40
80
65
ns
Cext = 80 pF,
Rext = 2 kΩ
tPHL
Clear
Q
tPLH
Clear
Q
—
35
55
ns
—
44
65
ns
70
120
150
Cext = 80 pF,
Rext = 2 kΩ
CL = 15 pF,
RL = 2 kΩ
20
47
70
Output pulse
width
tw (out)
A or B
Q or Q
600
670
750
ns
Cext = 0 pF,
Rext = 2 kΩ
Cext = 100 pF,
Rext = 10 kΩ
6
6.7
7.5
ms
Cext = 1 µF,
Rext = 10 kΩ
Caution in use
In order to prevent any malfunctions due to noise, connect a high frequency performance capacitor between Vcc and
GND, and keep the wiring between the External components and Cext, Rext/Cext pins as short as possible.
Testing Method
Test Circuit
A Input
P.G.
Zout = 50Ω
A
B Input
P.G.
Zout = 50Ω
CLR Input
P.G.
Zout = 50Ω
VCC
+–
Cext Rext
Cext Rext
/Cext Q
B
Q
CLR
Load circuit 1
RL
CL
Same as Load Circuit 1.
Notes: 1. CL includes probe and jig capacitance.
2. All diodes are 1S2074(H).
Rev.3.00, Jul.15.2005, page 4 of 8
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