MC54F258A データシートの表示（PDF） - Motorola => Freescale
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MC54F258A Datasheet PDF : 3 Pages
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MC74F258A
AC CHARACTERISTICS
Symbol
tPLH
tPHL
tPLH
tPHL
tPZH
tPZL
tPHZ
tPLZ
Parameter
Propagation Delay
In to Zn
Propagation Delay
S to Zn
Output Enable Time
Output Disable Time
74F
74F
TA = +25°C
TA = 0°C to 70°C
VCC = +5.0 V
VCC = 5.0 V ± 10%
CL = 50 pF
CL = 50 pF
Min
Max
Min
Max
Unit
2.5
5.3
2.0
6.0
ns
1.0
4.0
1.0
5.0
3.0
7.5
3.0
8.5
ns
2.5
7.0
2.5
8.0
2.0
6.0
2.0
7.0
ns
2.5
7.0
2.5
8.0
2.0
6.0
2.0
7.0
ns
1.5
6.0
1.5
7.0
FUNCTIONAL DESCRIPTION
The F258A is a quad 2-input multiplexer with 3-state out-
puts. It selects four bits of data from two sources under control
of a common Select input (S). When the Select input is LOW,
the I0x inputs are selected and when Select is HIGH, the I1x
inputs are selected. The data on the selected inputs appears
at the outputs in inverted form. The F258A is the logic imple-
mentation of a 4-pole, 2-position switch where the position of
the switch is determined by the logic levels supplied to the Se-
lect input. The logic equations for the outputs are shown be-
low:
Za = OE • (I1a • S + I0a • S)
Zb = OE • (I1b • S + I0b • S)
Zc = OE • (I1c • S + I0c • S)
Zd = OE • (I1d • S + I0d • S)
When the Output Enable input (OE) is HIGH, the outputs are
forced to a high impedance OFF state. If the outputs of the
3-state devices are tied together, all but one device must be in
the high impedance state to avoid high currents that would ex-
ceed the maximum ratings. Designers should ensure the Out-
put Enable signals to 3-state devices whose outputs are tied
together are designed so there is no overlap.
FAST AND LS TTL DATA
4-132
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