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HD74AC538
1-of-8 Decoder with 3-State Output
Description
The HD74AC538 decoder/demultiplexer accepts three Address (A0 to A2) input signal and decodes them
to select one of eight mutually exclusive outputs. A polarity control input (P) determines whether the
outputs are active LOW or active HIGH. A HIGH signal on either of the active LOW output Enable (OE)
inputs forces all outputs to the high impedance state. Two active HIGH and two active LOW input enables
are available for easy expansion to 1-of-32 decoding with four packages, or for data demultiplexing to 1-of8 or 1-of-16 destinations.
Features
• Output Polarity Control
• Data Demultiplexing Capability
• Multiple Enables for Expansion
• Outputs Source/Sink 24 mA
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HD74AC538
Pin Arrangement
O2
1
20
V
CC
Logic Symbol
2
O1
O0
3
OE1
4
OE2
5
A0
6
7
A1
O5
8
O6
9
GND
10 11
(Top view)
19
18
17
16
15
14
13
12
O3
O4
A2
E1
E2
E
E4
P
O
3
7
PA0
E1
E2
E3
E4
OE1
OE2
O0O1O2O3O4O5O6O7
2
A1 A2
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Pin Names
A0 to A2Address Inputs
E1, E
E3, E
Enable Inputs (Active LOW)
2
Enable Inputs (Active HIGH)
4
P Polarity Control Input
OE1, OE2Output Enable Inputs (Active LOW)
O0 to O73-State Outputs
Logic Diagram
A2
A1
A0
E
1
E2
E3
E4
HD74AC538
P
OE1
OE2
O7O6O5O4O3O2O1O0
3
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HD74AC538
Truth Table
Inputs Outputs
Function OE
High impedance H X XXXXXXXXZZZZZZZ
Disable L L H X X X X X X Outputs equal input
Active HIGH output L L L L H H L L L H L L LLLLL
(P = L) LLLLHHLLHLHLLLLLL
Active LOW output L L L L H H L L L L H H HHHHH
(P = L) LLLL HHL LHHLHHHHHH
H : High Voltage Level
L : Low Voltage Level
X : Immaterial
Z : High Impedance
1OE2E1E2E3E4A2A1A0O0O1O2O3O4O5O6O7
ZHXXXXXXXZZZZZZZZ
LLXHXXXXX
LLXXLXXXX
LLXXXLXXX
LLLLHHLHLLLHLLLLL
LLLLHHLHHLLLHLLLL
LLLLHHHLLLLLLHLLL
LLLLHHHLHLLLLLHLL
LLLLHHHHLLLLLLLHL
LLLLHHHHHLLLLLLLH
LLLL HHL HLHHLHHHHH
LLLL HHL HHHHHLHHHH
LLLLHHHLLHHHHLHHH
LLLLHHHLHHHHHHLHH
LLLL HHHHLHHHHHHLH
LLLL HHHHHHHHHHHHL
DC Characteristics (unless otherwise specified)
Item Symbol Max Unit Condition
Maximum quiescent supply current I
Maximum quiescent supply current I
4
CC
CC
80 µAV
8.0 µAV
= VCC or ground, VCC = 5.5 V,
IN
Ta = Worst case
= VCC or ground, VCC = 5.5 V,
IN
Ta = 25°C
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AC Characteristics: HD74AC538
HD74AC538
Item Symbol V
Propagation delay t
An to O
n
Propagation delay t
An to O
n
Propagation delay t
E
, or E2 to O
1
n
Propagation delay t
E
, or E2 to O
1
n
Propagation delay t
E
, or E4 to O
3
n
Propagation delay t
E
, or E4 to O
3
n
Propagation delay t
P to O
n
Propagation delay t
P to O
n
Propagation delay t
OE
to O
n
n
Propagation delay t
OE
to O
n
n
Propagation delay t
OE
to O
n
n
Propagation delay t
OE
to O
n
n
PLH
PHL
PLH
PHL
PLH
PHL
PLH
PHL
PZH
PZL
PHZ
PLZ
(V)*1Min Typ Max Min Max Unit
CC
3.3 1.0 10.5 17.5 1.0 20.0 ns
5.0 1.0 8.0 12.5 1.0 14.0
3.3 1.0 9.5 17.5 1.0 20.0 ns
5.0 1.0 7.0 12.0 1.0 14.0
3.3 1.0 11.0 19.5 1.0 23.0 ns
5.0 1.0 8.0 14.5 1.0 16.5
3.3 1.0 10.0 19.5 1.0 23.0 ns
5.0 1.0 8.0 14.0 1.0 16.5
3.3 1.0 11.0 19.5 1.0 23.0 ns
5.0 1.0 8.5 14.5 1.0 17.0
3.3 1.0 10.5 20.0 1.0 23.5 ns
5.0 1.0 8.0 15.0 1.0 18.0
3.3 1.0 10.5 15.5 1.0 17.5 ns
5.0 1.0 9.0 11.0 1.0 12.5
3.3 1.0 9.0 15.0 1.0 17.0 ns
5.0 1.0 7.5 10.5 1.0 11.5
3.3 1.0 7.0 14.0 1.0 15.5 ns
5.0 1.0 5.0 8.5 1.0 9.5
3.3 1.0 8.5 16.5 1.0 19.0 ns
5.0 1.0 5.5 9.5 1.0 11.5
3.3 1.0 7.0 14.0 1.0 15.5 ns
5.0 1.0 6.0 10.5 1.0 11.5
3.3 1.0 9.0 14.5 1.0 17.0 ns
5.0 1.0 7.0 10.5 1.0 12.0
Note: 1. Voltage Range 3.3 is 3.3 V ± 0.3 V
Voltage Range 5.0 is 5.0 V ± 0.5 V
Ta = +25°C
C
= 50 pF
L
Ta = –40°C to +85°C
CL = 50 pF
Capacitance
Item Symbol Typ Unit Condition
Input capacitance C
Power dissipation capacitance C
IN
PD
4.5 pF VCC = 5.5 V
100 pF VCC = 5.0 V
5
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24.50
25.40 Max
Unit: mm
1120
6.30
1
0.89
1.27 Max
2.54 ± 0.25
1.30
10
0.48 ± 0.10
7.00 Max
0.51 Min
2.54 Min 5.08 Max
Hitachi Code
JEDEC
EIAJ
Weight
7.62
+ 0.11
0.25
– 0.05
0° – 15°
(reference value)
DP-20N
—
Conforms
1.26 g
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20
Unit: mm
12.6
13 Max
11
5.5
1
0.80 Max
1.27
*0.42 ± 0.08
0.40 ± 0.06
*Dimension including the plating thickness
Base material dimension
10
0.12
0.10 ± 0.10
0.15
M
2.20 Max
7.80
0.20 ± 0.04
*0.22 ± 0.05
0.70 ± 0.20
Hitachi Code
JEDEC
EIAJ
Weight
(reference value)
+ 0.20
– 0.30
1.15
0° – 8°
FP-20DA
—
Conforms
0.31 g
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20
Unit: mm
12.8
13.2 Max
11
7.50
1
0.935 Max
1.27
*0.42 ± 0.08
0.40 ± 0.06
*Dimension including the plating thickness
Base material dimension
10
0.12
0.20 ± 0.10
0.15
2.65 Max
M
10.40
0.25 ± 0.04
*0.27 ± 0.05
0.70
Hitachi Code
JEDEC
EIAJ
Weight
(reference value)
+ 0.25
– 0.40
1.45
+ 0.57
– 0.30
0° – 8°
FP-20DB
Conforms
—
0.52 g
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20 11
110
+0.08
*0.22
–0.07
0.20 ± 0.06
6.50
6.80 Max
0.65 Max
0.65
0.13
Unit: mm
4.40
1.0
M
6.40 ± 0.20
0.10
1.10 Max
*Dimension including the plating thickness
Base material dimension
0.15 ± 0.04
*0.17 ± 0.05
+0.03
–0.04
0.07
0° – 8°
Hitachi Code
JEDEC
EIAJ
(reference value)
Weight
0.50 ± 0.10
TTP-20DA
—
—
0.07 g
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received the latest product standards or specifications before final design, purchase or use.
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contact Hitachi’s sales office before using the product in an application that demands especially high
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4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly
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