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
nI
CC
reduced by 50%
nDemultiplexing capability
nMultiple input enable for easy expansion
nActive LOW mutually exclusive outputs
nOutputs source/sink 24 mA
n’ACT138 has TTL-compatible inputs
nStandard 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
HXXXXXHHHHHHHH
XHXXXXHHHHHHHH
XXLXXXHHHHHHHH
LLHLLLLHHHHHHH
LLHHLLHLHHHHHH
LLHLHLHHLHHHHH
LLHHHLHHHLHHHH
LLHLLHHHHHLHHH
LLHHLHHHHHHLHH
LLHLHHHHHHHHLH
LLHHHHHHHHHHHL
H
=
HIGH Voltage Level
L=LOW Voltage Level
X=Immaterial
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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
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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
) −65˚C to +150˚C
Junction Temperature (T
J
)
CDIP 175˚C
Recommended Operating
Conditions
Supply Voltage (V
CC
)
’AC 2.0V to 6.0V
’ACT 4.5V to 5.5V
Input Voltage (V
I
) 0VtoV
CC
Output Voltage (V
O
) 0VtoV
CC
Operating Temperature (T
A
)
54AC/ACT −55˚C to +125˚C
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) −55˚C to +125˚C
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 µA
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 µA
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 µA 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
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DC Characteristics for ’AC Family Devices (Continued)
54AC
Symbol Parameter V
CC
T
A
=Units Conditions
(V) −55˚C to +125˚C
Guaranteed Limits
I
CC
Maximum
Quiescent Supply
Current 5.5 80.0 µA V
IN
=V
CC
or GND
Note 2: All outputs loaded; thresholds on input associated with output under test.
Note 3: Maximum test duration 2.0 ms, one output loaded at a time.
Note 4: IIN and ICC @3.0V are guaranteed to be less than or equal to the respective limit @5.5V VCC.I
CC for 54AC @25˚C is identical to 74AC @25˚C.
DC Characteristics for ’ACT Family Devices
54ACT
Symbol Parameter V
CC
T
A
=Units Conditions
(V) −55˚C to +125˚C
Guaranteed Limits
V
IH
Minimum High
Level Input Voltage 4.5 2.0 V V
OUT
=0.1V
5.5 2.0 or V
CC
− 0.1V
V
IL
Maximum Low
Level Input Voltage 4.5 0.8 V V
OUT
=0.1V
5.5 0.8 or V
CC
− 0.1V
V
OH
Minimum High
Level Output
Voltage
4.5 4.4 V I
OUT
=−50 µA
5.5 5.4 (Note 5) V
IN
=V
IL
or V
IH
4.5 3.70 V I
OH
−24 mA
5.5 4.70 −24 mA
V
OL
Maximum Low
Level Output
Voltage
4.5 0.1 V I
OUT
=50 µA
5.5 0.1 (Note 5) V
IN
=V
IL
or V
IH
4.5 0.50 V I
OL
24 mA
5.5 0.50 24 mA
I
IN
Maximum Input 5.5 ±1.0 µA V
I
=V
CC
, GND
Leakage Current
I
CCT
Maximum 5.5 1.6 mA V
I
=V
CC
− 2.1V
I
CC
/Input
I
OLD
(Note 6) Minimum
Dynamic Output
Current
5.5 50 mA V
OLD
=1.65V Max
I
OHD
5.5 −50 mA V
OHD
=3.85V Min
I
CC
Maximum
Quiescent Supply
Current 5.5 80.0 µA V
IN
=V
CC
or GND
Note 5: All outputs loaded; thresholds on input associated with output under test.
Note 6: Maximum test duration 2.0 ms, one output loaded at a time.
Note 7: ICC for 54ACT @25˚C is identical to 74ACT @25˚C.
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AC Electrical Characteristics
54AC
V
CC
T
A
=−55˚C Fig.
Symbol Parameter (V) to +125˚C Units No.
(Note 8) C
L
=50 pF
Min Max
t
PLH
Propagation Delay 3.3 1.0 16.0 ns
A
n
to O
n
5.0 1.5 12.0
t
PHL
Propagation Delay 3.3 1.0 15.0 ns
A
n
to O
n
5.0 1.5 11.5
t
PLH
Propagation Delay 3.3 1.0 16.5 ns
E
1
or E
2
to O
n
5.0 1.5 13.0
t
PHL
Propagation Delay 3.3 1.0 15.5 ns
E
1
or E
2
to O
n
5.0 1.5 12.0
t
PLH
Propagation Delay 3.3 1.0 17.0 ns
E
3
to O
n
5.0 1.5 13.5
t
PHL
Propagation Delay 3.3 1.0 15.0 ns
E
3
to O
n
5.0 1.5 11.0
Note 8: Voltage Range 3.3 is 3.3V ±0.3V
Voltage Range 5.0 is 5.0V ±0.5V
AC Electrical Characteristics
54ACT
V
CC
T
A
=−55˚C Fig.
Symbol Parameter (V) to +125˚C Units No.
(Note 9) C
L
=50 pF
Min Max
t
PLH
Propagation Delay 5.0 1.5 12.5 ns
A
n
to O
n
t
PHL
Propagation Delay 5.0 1.5 12.5 ns
A
n
to O
n
t
PLH
Propagation Delay 5.0 1.5 13.5 ns
E
1
or E
2
to O
n
t
PHL
Propagation Delay 5.0 1.5 12.5 ns
E
1
or E
2
to O
n
t
PLH
Propagation Delay 5.0 1.5 14.0 ns
E
3
toOn
t
PHL
Propagation Delay 5.0 1.5 12.0 ns
E
3
toOn
Note 9: Voltage Range 5.0 is 5.0V ±0.5V
Capacitance
Symbol Parameter Typ Units Conditions
C
IN
Input Capacitance 4.5 pF V
CC
=OPEN
C
PD
Power Dissipation 60.0 pF V
CC
=5.0V
Capacitance
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8
Physical Dimensions inches (millimeters) unless otherwise noted
20 Terminal Ceramic Leadless Chip Carrier (L)
NS Package Number E20A
16 Lead Ceramic Dual-In-Line Package (D)
NS Package Number J16A
9 www.national.com
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DE-
VICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMI-
CONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or sys-
tems which, (a) are intended for surgical implant into
the body, or (b) support or sustain life, and whose fail-
ure to perform when properly used in accordance
with instructions for use provided in the labeling, can
be reasonably expected to result in a significant injury
to the user.
2. A critical component in any component of a life support
device or system whose failure to perform can be rea-
sonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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16 Lead Ceramic Flatpak (F)
NS Package Number W16A
54AC138
•
54ACT138 1-of-8 Decoder/Demultiplexer
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
