MC74HC251A
http://onsemi.com
4
AC ELECTRICAL CHARACTERISTICS (C
L
= 50 pF, Input t
r
= t
f
= 6 ns)
Symbol Parameter
V
CC
V
Guaranteed Limit
Unit
− 55 to
25°C
v 85°C v 125°C
t
PLH
,
t
PHL
Maximum Propagation Delay, Input D to Output Y or Y
(Figures 2, 3 and 6)
2.0
4.5
6.0
185
37
31
230
46
39
280
56
48
ns
t
PLH
,
t
PHL
Maximum Propagation Delay, Input A to Output Y or Y
(Figures 3 and 6)
2.0
4.5
6.0
205
41
35
255
51
43
310
62
53
ns
t
PLZ
,
t
PHZ
Maximum Propagation Delay, Output Enable to Output Y
(Figures 5 and 7)
2.0
4.5
6.0
195
39
33
245
49
42
295
59
50
ns
t
PZL
,
t
PZH
Maximum Propagation Delay, Output Enable to Output Y
(Figures 5 and 7)
2.0
4.5
6.0
145
29
25
180
36
31
220
44
38
ns
t
PLZ
,
t
PHZ
Maximum Propagation Delay, Output Enable to Output Y
(Figures 5 and 7)
2.0
4.5
6.0
220
44
37
275
55
47
330
66
56
ns
t
PZL
,
t
PZH
Maximum Propagation Delay, Output Enable to Output Y
(Figures 5 and 7)
2.0
4.5
6.0
150
30
26
190
38
33
225
45
38
ns
t
TLH
,
t
THL
Maximum Output Transition Time, Any Output
(Figures 2 and 6)
2.0
4.5
6.0
75
15
13
95
19
16
110
22
19
ns
C
in
Maximum Input Capacitance − 10 10 10 pF
C
out
Maximum Three−State Output Capacitance
(Output in High−Impedance
State)
− 15 15 15 pF
C
PD
Power Dissipation Capacitance (Per Package)
Typical @ 25°C, V
CC
= 5.0 V
pF
36
PIN DESCRIPTIONS
INPUTS
D0, D1, …, D7 (Pins 4, 3, 2, 1, 15, 14, 13, 12)
Data inputs. Data on one of these eight binary inputs may
be selected to appear on the output.
CONTROL INPUTS
A0, A1, A2 (Pins 11, 10, 9)
Address inputs. The data on these pins are the binary
address of the selected input (see the Function Table).
Output Enable (Pin 7)
Output Enable. This input pin must be at a low level for
the selected data to appear at the outputs. If the Output
Enable pin is high, both the Y and Y
outputs are taken to the
high−impedance state.
OUTPUTS
Y, Y (Pins 5, 6)
Data outputs. The selected data is presented at these pins
in both true (Y output) and complemented (Y
output) forms.
