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Электронный компонент: 5962R8755401SFA

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54AC138
54ACT138
1-of-8 Decoder/Demultiplexer
General Description
The
'AC/'ACT138
is
a
high-speed
1-of-8
decoder/
demultiplexer. This device is ideally suited for high-speed bi-
polar memory chip select address decoding. The multiple in-
put enables allow parallel expansion to a 1-of-24 decoder
using just three 'AC/'ACT138 devices or a 1-of-32 decoder
using four 'AC/'ACT138 devices and one inverter.
Features
n
I
CC
reduced by 50%
n
Demultiplexing capability
n
Multiple input enable for easy expansion
n
Active LOW mutually exclusive outputs
n
Outputs source/sink 24 mA
n
'ACT138 has TTL-compatible inputs
n
Standard Microcircuit Drawing (SMD)
-- 'AC138: 5962-87622
-- 'ACT138: 5962-87554
Logic Symbols
Pin Names
Description
A
0
A
2
Address Inputs
E
1
E
2
Enable Inputs
E
3
Enable Input
O
0
O
7
Outputs
Connection Diagrams
FACT
is a registered trademark of Fairchild Semiconductor Corporation.
DS100268-1
IEEE/IEC
DS100268-7
Pin Assignment
for DIP and Flatpak
DS100268-2
Pin Assignment
for LCC
DS100268-3
August 1998
54AC138
54ACT138
1-of-8
Decoder/Demultiplexer
1998 National Semiconductor Corporation
DS100268
www.national.com
Functional Description
The 'AC/'ACT138 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 out-
puts (O
0
O
7
). The 'AC/'ACT138 features three Enable in-
puts, 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 enable function allows easy parallel ex-
pansion of the device to a 1-of-32 (5 lines to 32 lines) de-
coder with just four 'AC/'ACT138 devices and one inverter
(see
Figure 1). The 'AC/'ACT138 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
Enable inputs which are not used must be permanently tied
to their appropriate active-HIGH or active-LOW state.
Truth Table
Inputs
Outputs
E
1
E
2
E
3
A
0
A
1
A
2
O
0
O
1
O
2
O
3
O
4
O
5
O
6
O
7
H
X
X
X
X
X
H
H
H
H
H
H
H
H
X
H
X
X
X
X
H
H
H
H
H
H
H
H
X
X
L
X
X
X
H
H
H
H
H
H
H
H
L
L
H
L
L
L
L
H
H
H
H
H
H
H
L
L
H
H
L
L
H
L
H
H
H
H
H
H
L
L
H
L
H
L
H
H
L
H
H
H
H
H
L
L
H
H
H
L
H
H
H
L
H
H
H
H
L
L
H
L
L
H
H
H
H
H
L
H
H
H
L
L
H
H
L
H
H
H
H
H
H
L
H
H
L
L
H
L
H
H
H
H
H
H
H
H
L
H
L
L
H
H
H
H
H
H
H
H
H
H
H
L
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
www.national.com
2
Logic Diagram
DS100268-4
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
3
www.national.com
Logic Diagram
(Continued)
DS100268-5
FIGURE
1.
Expansion
to
1-of-32
Decoding
www.national.com
4
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (V
CC
)
-0.5V to +7.0V
DC Input Diode Current (I
IK
)
V
I
= -0.5V
V
I
= V
CC
+ 0.5V
-20 mA
+20 mA
DC Input Voltage (V
I
)
-0.5V to V
CC
+ 0.5V
DC Output Diode Current (I
OK
)
V
O
= -0.5V
V
O
= V
CC
+ 0.5V
-20 mA
+20 mA
DC Output Voltage (V
O
)
-0.5V to V
CC
+ 0.5V
DC Output Source
or Sink Current (I
O
)
50 mA
DC V
CC
or Ground Current
per Output Pin (I
CC
or I
GND
)
50 mA
Storage Temperature (T
STG
)
-65C to +150C
Junction Temperature (T
J
)
CDIP
175C
Recommended Operating
Conditions
Supply Voltage (V
CC
)
'AC
2.0V to 6.0V
'ACT
4.5V to 5.5V
Input Voltage (V
I
)
0V to V
CC
Output Voltage (V
O
)
0V to V
CC
Operating Temperature (T
A
)
54AC/ACT
-55C to +125C
Minimum Input Edge Rate (
V/
t)
'AC Devices
V
IN
from 30% to 70% of V
CC
V
CC
@
3.3V, 4.5V, 5.5V
125 mV/ns
Minimum Input Edge Rate (
V/
t)
'ACT Devices
V
IN
from 0.8V to 2.0V
V
CC
@
4.5V, 5.5V
125 mV/ns
Note 1: Absolute maximum ratings are those values beyond which damage
to the device may occur. The databook specifications should be met, without
exception, to ensure that the system design is reliable over its power supply,
temperature, and output/input loading variables. National does not recom-
mend operation of FACT
circuits outside databook specifications.
DC Characteristics for 'AC Family Devices
54AC
Symbol
Parameter
V
CC
T
A
=
Units
Conditions
(V)
-55C to +125C
Guaranteed Limits
V
IH
Minimum High
Level Input Voltage
3.0
2.1
V
OUT
= 0.1V
4.5
3.15
V
or V
CC
- 0.1V
5.5
3.85
V
IL
Maximum Low
Level Input Voltage
3.0
0.9
V
OUT
= 0.1V
4.5
1.35
V
or V
CC
- 0.1V
5.5
1.65
V
OH
Minimum High
Level Output
Voltage
3.0
2.9
I
OUT
= -50 A
4.5
4.4
V
5.5
5.4
(Note 2) V
IN
= V
IL
or V
IH
3.0
2.4
-12 mA
4.5
3.7
V
I
OH
-24 mA
5.5
4.7
-24 mA
V
OL
Maximum Low
Level Output
Voltage
3.0
0.1
I
OUT
= 50 A
4.5
0.1
V
5.5
0.1
(Note 2) V
IN
= V
IL
or V
IH
3.0
0.50
12 mA
4.5
0.50
V
I
OL
24 mA
5.5
0.50
24 mA
I
IN
Maximum Input
5.5
1.0
A
V
I
= V
CC
, GND
Leakage Current
I
OLD
(Note 3) Minimum
Dynamic Output
Current
5.5
50
mA
V
OLD
= 1.65V Max
I
OHD
5.5
-50
mA
V
OHD
= 3.85V Min
5
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