HD74AC138/HD74ACT138
1-of-8 Decoder/Demultiplexer
REJ03D0248–0200Z
(Previous ADE-205-368 (Z))
Rev.2.00
Jul.16.2004
Description
The HD74AC138/HD74ACT138 is a high-speed 1-of-8 decoder/demultiplexer. This device is ideally suited for high-
speed bipolar memory chip select address decoding. The multiple input enables allow parallel expansion to a 1-of-24
decoder using just three HD74AC138/HD74ACT138 devices or a 1-of-32 decoder using four
HD74AC138/HD74ACT138 devices and one inverter.
Features
•
Demultiplexing Capability
•
Multiple Input Enable for Easy Expansion
•
Active LOW Mutually Exclusive Outputs
•
Outputs Source/Sink 24 mA
•
HD74ACT138 has TTL-Compatible Inputs
•
Ordering Information: Ex. HD74AC138
Part Name
HD74AC138AP
Package Type
DIP-16 pin
Package Code Package Abbreviation Taping Abbreviation (Quantity)
DP-16E, -16FV
FP-16DAV
TTP-16DAV
P
FP
RP
T
—
EL (2,000 pcs/reel)
EL (2,500 pcs/reel)
ELL(2,000 pcs/reel)
HD74AC138AFPEL SOP-16 pin (JEITA)
HD74AC138TELL
TSSOP-16 pin
HD74AC138ARPEL SOP-16 pin (JEDEC) FP-16DNV
Notes: 1. Please consult the sales office for the above package availability.
2. The packages with lead-free pins are distinguished from the conventional products by adding V at the end of
the package code.
Pin Arrangement
A
0
1
A
1
2
A
2
3
E
1
4
E
2
5
E
3
6
O
7
7
GND 8
(Top view)
16 V
CC
15
O
0
14
O
1
13
O
2
12
O
3
11
O
4
10
O
5
9
O
6
Rev.2.00, Jul.16.2004, page 1 of 9
HD74AC138/HD74ACT138
Logic Symbol
A
0
A
1
A
2
E
1
E
2
E
3
O
0
O
1
O
2
O
3
O
4
O
5
O
6
O
7
Pin Names
A
0
to A
2
E
1
to
E
2
E
3
O
0
to
O
7
Address Inputs
Enable Inputs
Enable Input
Outputs
Functional Description
The HD74AC138/HD74ACT138 high-speed 1-of-8 decoder/demultiplexer accepts three binary weighted inputs (A
0
, A
1
,
A
2
) and, when enabled, provides eight mutually exclusive active-LOW outputs (O
0
to
O
7
). The
HD74AC138/HD74ACT138 features three Enable inputs, two active-Low (E
1
,
E
2
) and one active-High (E
3
). All
outputs will be High unless
E
1
and
E
2
are Low and E
3
is High. This multiple enabled function allows easy parallel
expansion of the device to a 1-of-32 (5 lines to 32 lines) decoder with just four HD74AC138/HD74ACT138 devices
and one inverter (See Figure a). The HD74AC138/HD74ACT138 can be used as an 8-output demultiplexer by using
one of the active Low Enable inputs as the data input and the other Enable inputs as strobes. The Enables inputs which
are not used must be permanently tied to their appropriate active-High or active-Low state.
Truth Table
Inputs
E
1
H
X
X
L
L
L
L
L
L
L
L
H :
L :
X :
E
2
X
H
X
L
L
L
L
L
L
L
L
X
X
L
H
H
H
H
H
H
H
H
E
3
X
X
X
L
H
L
H
L
H
L
H
A
0
X
X
X
L
L
H
H
L
L
H
H
A
1
X
X
X
L
L
L
L
H
H
H
H
A
2
H
H
H
L
H
H
H
H
H
H
H
O
0
H
H
H
H
L
H
H
H
H
H
H
O
1
H
H
H
H
H
L
H
H
H
H
H
O
2
H
H
H
H
H
H
L
H
H
H
H
Outputs
O
3
H
H
H
H
H
H
H
L
H
H
H
O
4
H
H
H
H
H
H
H
H
L
H
H
O
5
H
H
H
H
H
H
H
H
H
L
H
O
6
H
H
H
H
H
H
H
H
H
H
L
O
7
High Voltage Level
Low Voltage Level
Immaterial
Rev.2.00, Jul.16.2004, page 2 of 9
HD74AC138/HD74ACT138
Logic Diagram
A
2
A
1
A
0
E
1
E
2
E
3
O
7
O
6
O
5
O
4
O
3
O
2
O
1
O
0
Please note that this diagram is provided only for the understanding of logic operations and should not be
used to estimate propagation delays.
Figure a: Expansion of 1-of-32 Decoding
A
0
A
1
A
2
Õ04
A
3
A
4
H
123
A
0
A
1
A
2
E
A
0
A
1
A
2
123
E
A
0
A
1
A
2
123
E
A
0
A
1
A
2
123
E
O
0
O
1
O
2
O
3
O
4
O
5
O
6
O
7
O
0
O
0
O
1
O
2
O
3
O
4
O
5
O
6
O
7
O
0
O
1
O
2
O
3
O
4
O
5
O
6
O
7
O
0
O
1
O
2
O
3
O
4
O
5
O
6
O
7
O
31
Absolute Maximum Ratings
Item
Supply voltage
DC input diode current
DC input voltage
DC output diode current
DC output voltage
DC output source or sink current
DC V
CC
or ground current per output pin
Storage temperature
Symbol
V
CC
I
IK
V
I
I
OK
V
O
I
O
I
CC
, I
GND
Tstg
Ratings
–0.5 to 7
–20
20
–0.5 to Vcc+0.5
–50
50
–0.5 to Vcc+0.5
±50
±50
–65 to +150
Unit
V
mA
mA
V
mA
mA
V
mA
mA
°C
Condition
V
I
= –0.5V
V
I
= Vcc+0.5V
V
O
= –0.5V
V
O
= Vcc+0.5V
Rev.2.00, Jul.16.2004, page 3 of 9
HD74AC138/HD74ACT138
Recommended Operating Conditions: HD74AC138
Item
Supply voltage
Input and output voltage
Operating temperature
Input rise and fall time
(except Schmitt inputs)
V
IN
30% to 70% V
CC
Symbol
V
CC
V
I
, V
O
Ta
tr, tf
Ratings
2 to 6
0 to V
CC
–40 to +85
8
V
V
°C
ns/V
V
CC
= 3.0V
V
CC
= 4.5 V
V
CC
= 5.5 V
Unit
Condition
DC Characteristics: HD74AC138
Item
Sym-
bol
V
IH
Vcc
(V)
3.0
4.5
5.5
V
IL
3.0
4.5
5.5
3.0
4.5
5.5
3.0
4.5
V
OL
5.5
3.0
4.5
5.5
3.0
4.5
Input leakage
current
Dynamic output
current*
Quiescent supply
current
I
IN
I
OLD
I
OHD
I
CC
5.5
5.5
5.5
5.5
5.5
min.
2.1
3.15
3.85
—
—
—
2.9
4.4
5.4
2.58
3.94
4.94
—
—
—
—
—
—
—
—
—
—
Ta = 25°C
°
typ.
1.5
2.25
2.75
1.50
2.25
2.75
2.99
4.49
5.49
—
—
—
0.002
0.001
0.001
—
—
—
—
—
—
—
max.
—
—
—
0.9
1.35
1.65
—
—
—
—
—
—
0.1
0.1
0.1
0.32
0.32
0.32
±0.1
—
—
8.0
Ta = –40 to
+85°C
°
min.
2.1
3.15
3.85
—
—
—
2.9
4.4
5.4
2.48
3.80
4.80
—
—
—
—
—
—
—
86
–75
—
max.
—
—
—
0.9
1.35
1.65
—
—
—
—
—
—
0.1
0.1
0.1
0.37
0.37
0.37
±1.0
—
—
80
µA
mA
mA
µA
V
V
OUT
= 0.1 V or V
CC
–0.1 V
Unit
Condition
Input Voltage
V
V
OUT
= 0.1 V or V
CC
–0.1 V
Output voltage
V
OH
V
IN
= V
IL
or V
IH
I
OUT
= –50
µA
V
IN
= V
IL
or V
IH
I
OH
= –12 mA
I
OH
= –24 mA
I
OH
= –24 mA
V
IN
= V
IL
or V
IH
I
OUT
= 50
µA
V
IN
= V
IL
or V
IH
I
OL
= 12 mA
I
OL
= 24 mA
I
OL
= 24 mA
V
IN
= V
CC
or GND
V
OLD
= 1.1 V
V
OHD
= 3.85 V
V
IN
= V
CC
or ground
*Maximum
test duration 2.0 ms, one output loaded at a time.
Recommended Operating Conditions: HD74ACT138
Item
Supply voltage
Input and output voltage
Operating temperature
Input rise and fall time
(except Schmitt inputs)
V
IN
0.8 to 2.0 V
Symbol
V
CC
V
I
, V
O
Ta
tr, tf
2 to 6
0 to V
CC
–40 to +85
8
Ratings
V
V
°C
ns/V
V
CC
= 4.5V
V
CC
= 5.5V
Unit
Condition
Rev.2.00, Jul.16.2004, page 4 of 9
HD74AC138/HD74ACT138
DC Characteristics: HD74ACT138
Item
Sym-
bol
V
IH
V
IL
Output voltage
V
OH
V
CC
(V)
4.5
5.5
4.5
5.5
4.5
5.5
4.5
V
OL
5.5
4.5
5.5
4.5
Input current
I
CC
/input current
Dynamic output
current*
Quiescent supply
current
I
IN
I
CCT
I
OLD
I
OHD
I
CC
5.5
5.5
5.5
5.5
5.5
5.5
min.
2.0
2.0
—
—
4.4
5.4
3.94
4.94
—
—
—
—
—
—
—
—
—
Ta = 25°C
°
typ.
1.5
1.5
1.5
1.5
4.49
5.49
—
—
0.001
0.001
—
—
—
0.6
—
—
—
max.
—
—
0.8
0.8
—
—
—
—
0.1
0.1
0.32
0.32
±0.1
—
—
—
8.0
Ta = –40 to
+85°C
°
min.
2.0
2.0
—
—
4.4
5.4
3.80
4.80
—
—
—
—
—
—
86
–75
—
max.
—
—
0.8
0.8
—
—
—
—
0.1
0.1
0.37
0.37
±1.0
1.5
—
—
80
µA
mA
mA
mA
µA
V
Unit
Condition
Input voltage
V
V
OUT
= 0.1 V or Vcc–0.1 V
V
OUT
= 0.1 V or Vcc–0.1 V
V
IN
= V
IL
or V
IH
I
OUT
= –50
µA
V
IN
= V
IL
V
IN
= V
IL
or V
IH
I
OUT
= 50
µA
V
IN
= V
IL
V
IN
= V
CC
or GND
V
IN
= V
CC
–2.1 V
V
OLD
= 1.1 V
V
OHD
= 3.85 V
V
IN
= V
CC
or ground
I
OL
= 24 mA
I
OL
= 24 mA
I
OH
= –24 mA
I
OH
= –24 mA
*Maximum
test duration 2.0 ms, one output loaded at a time.
AC Characteristics: HD74AC138
Ta = +25°C
C
L
= 50 pF
Item
Propagation delay
A
n
to
O
n
Propagation delay
A
n
to
O
n
Propagation delay
E
1
or
E
2
to
O
n
Propagation delay
E
1
or
E
2
to
O
n
Propagation delay
E
3
to
O
n
Propagation delay
E
3
to
O
n
Note:
Symbol
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
V
CC
(V)*
1
Min
3.3
1.0
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
1. Voltage Range 3.3 is 3.3 V ± 0.3 V
Voltage Range 5.0 is 5.0 V ± 0.5 V
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Typ
8.5
6.5
8.0
6.0
11.0
8.0
9.5
7.0
11.0
8.0
8.5
6.0
Max
13.0
9.5
12.5
9.0
15.0
11.0
13.5
9.5
15.5
11.0
13.0
8.0
Ta = –40°C to +85°C
C
L
= 50 pF
Min
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Max
15.0
10.5
14.0
10.5
16.0
12.0
15.0
10.5
16.5
12.5
14.0
9.5
Unit
ns
ns
ns
ns
ns
ns
Rev.2.00, Jul.16.2004, page 5 of 9
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