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HD74LS191 Datasheet, PDF (5/11 Pages) Hitachi Semiconductor – Synchronous Up/Down 4-bit Binary Counters(single clock line)
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HD74LS191
Switching Characteristics
(VCC = 5 V, Ta = 25°C)
Item
Symbol Inputs
Outputs
min.
typ.
max.
Unit Condition
Maximum clock
frequency
ƒmax
Clock
QA, QB, QC, QD
20
25
—
MHz
tPLH
tPHL
—
Load
QA, QB, QC, QD
—
22
33
33
50
ns
tPLH
tPHL
Data A,
—
B, C, D
QA, QB, QC, QD
—
20
27
32
40
ns
tPLH
—
Clock
Ripple Clock
13
20
ns
tPHL
—
16
24
Propagation
delay time
tPLH
tPHL
—
Clock
QA, QB, QC, QD
—
16
24
24
36
ns
CL = 15 pF,
RL = 2 kΩ
tPLH
Clock
Max / Min
tPHL
—
28
42
ns
—
37
52
tPLH
Down /
Ripple Clock
—
30
45
ns
tPHL
Up
—
30
45
tPLH
Down /
Max / Min
tPHL
Up
—
21
33
ns
—
22
33
tPLH
Enable
Ripple Clock
—
21
33
ns
tPHL
—
22
33
Rev.2.00, Feb.18.2005, page 5 of 10
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