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Электронный компонент: HD74HCT238

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HD74HCT238
3-to-8-line Decoder/Demultiplexer
Description
The HD74HCT238 has 3 binary select inputs (A, B, and C). If the device is enabled these inputs
determined which one of the eight normally high outputs will go low. Two active low and one active high
enables (G
1
, G
2A
and G
2B
) are provided to ease the cascading of decoders.
Features
LSTTL Output Logic Level Compatibility as well as CMOS Output Compatibility
High Speed Operation: t
pd
(A, B, C to Y) = 18.5 ns typ (C
L
= 50 pF)
High Output Current: Fanout of 10 LSTTL Loads
Wide Operating Voltage: V
CC
= 4.5 to 5.5 V
Low Input Current: 1 A max
Low Quiescent Supply Current: I
CC
(static) = 4 A max (Ta = 25C)
HD74HCT238
2
Function Table
Inputs
Enable
Select
Outputs
G
1
G
2A
G
2B
C
B
A
Y
0
Y
1
Y
2
Y
3
Y
4
Y
5
Y
6
Y
7
X
X
H
X
X
X
L
L
L
L
L
L
L
L
X
H
X
X
X
X
L
L
L
L
L
L
L
L
L
X
X
X
X
X
L
L
L
L
L
L
L
L
H
L
L
L
L
L
H
L
L
L
L
L
L
L
H
L
L
L
L
H
L
H
L
L
L
L
L
L
H
L
L
L
H
L
L
L
H
L
L
L
L
L
H
L
L
L
H
H
L
L
L
H
L
L
L
L
H
L
L
H
L
L
L
L
L
L
H
L
L
L
H
L
L
H
L
H
L
L
L
L
L
H
L
L
H
L
L
H
H
L
L
L
L
L
L
L
H
L
H
L
L
H
H
H
L
L
L
L
L
L
L
H
Pin Arrangement
1
2
3
4
5
6
7
8
A
B
C
G
2A
G
2B
G
1
Y
7
GND
V
CC
Y
0
Y
1
Y
2
Y
3
Y
4
Y
5
Y
6
16
15
14
13
12
11
10
9
(Top view)
B
C
G
2A
G
2B
G
1
Y
7
Y
0
Y
1
Y
2
Y
3
Y
4
Y
5
Y
6
A
Outputs
Outputs
Enable
Inputs
Select
Inputs
HD74HCT238
3
Logic Diagram
Y
0
Y
1
Y
2
Y
3
Y
4
Y
5
Y
6
Y
7
G
1
B
A
C
G
2A
G
2B
DC Characteristics
Ta = 25
C
Ta = 40 to
+85
C
Test Conditions
Item
Symbol
Min Typ Max Min
Max
Unit
V
CC
(V)
Input voltage
V
IH
2.0
--
--
2.0
--
V
4.5 to
5.5
V
IL
--
--
0.8
--
0.8
V
4.5 to
5.5
Output voltage
V
OH
4.4
--
--
4.4
--
V
4.5
Vin = V
IH
or V
IL
I
OH
= 20
A
4.18 --
--
4.13
--
4.5
I
OH
= 4 mA
V
OL
--
--
0.1
--
0.1
V
4.5
Vin = V
IH
or V
IL
I
OL
= 20
A
--
--
0.26 --
0.33
4.5
I
OL
= 4 mA
Input current
Iin
--
--
0.1 --
1.0
A
5.5
Vin = V
CC
or GND
Quiescent supply
current
I
CC
--
--
4.0
--
40
A
5.5
Vin = V
CC
or GND, Iout = 0
A
HD74HCT238
4
AC Characteristics (C
L
= 50 pF, Input t
r
= t
f
= 6 ns)
Ta = 25
C
Ta = 40 to
+85
C
Test Conditions
Item
Symbol
Min Typ Max Min
Max
Unit
V
CC
(V)
Propagation delay t
PLH
--
18
30
--
38
ns
4.5
A, B or C to Y
time
t
PHL
--
19
30
--
38
4.5
t
PLH
--
17
30
--
38
ns
4.5
G
2A
to Y
t
PHL
--
17
30
--
39
4.5
t
PLH
--
17
30
--
38
ns
4.5
G
2B
to Y
t
PHL
--
17
30
--
38
4.5
t
PLH
--
17
30
--
38
ns
4.5
G
1
to Y
t
PHL
--
17
30
--
38
4.5
Output rise/fall
time
t
TLH
t
THL
--
5
15
--
19
ns
4.5
Input capacitance
Cin
--
5
10
--
10
pF
--
Hitachi Code
JEDEC
EIAJ
Weight (reference value)
DP-16
Conforms
Conforms
1.07 g
Unit: mm
6.30
19.20
16
9
8
1
1.3
20.00 Max
7.40 Max
7.62
0.25
+ 0.13
0.05
2.54
0.25
0.48
0.10
0.51 Min
2.54 Min
5.06 Max
0
15
1.11 Max