54FCT138 1-of-8 Decoder/Demultiplexer
October 1999
54FCT138
1-of-8 Decoder/Demultiplexer
General Description
The FCT138 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 al-
low parallel expansion to a 1-of-24 decoder using just three
FCT138 devices or a 1-of-32 decoder using four FCT138 de-
vices and one inverter.
Features
Demultiplexing capability
Multiple input enable for easy expansion
Active LOW mutually exclusive outputs
Outputs sink capability of 32mA, source capability of
12mA
n
TTL input and output level compatible
n
CMOS power consumption
n
Standard Microcircuit Drawing (SMD) 5962-8765401
n
n
n
n
Ordering Code
Military
54FCT138DMQB
54FCT138FMQB
54FCT138LMQB
Package
Number
J16A
W16A
E20A
16-Lead Ceramic Dual-In-Line
16-Lead Cerpack
20-Lead Ceramic Leadless Chip Carrier, Type C
Package Description
Logic Symbols
Connection Diagrams
Pin Assignment
for DIP and Flatpak
DS100963-1
IEEE/IEC
DS100963-2
Pin Assignment
for LCC
DS100963-7
Pin Names
A
0
–A
2
E
1
–E
2
E
3
O
0
–O
7
Description
Address Inputs
Enable Inputs
Enable Input
Outputs
DS100963-3
FACT
®
is a registered trademark of Fairchild Semiconductor Corporation.
© 1999 National Semiconductor Corporation
DS100963
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54FCT138
Functional Description
The FCT138 high-speed 1-of-8 decoder/demultiplexer ac-
cepts 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 FCT138 features three Enable inputs,
two active-LOW (E
1
, E
2
) and one active-HIGH (E
3
). All out-
puts will be HIGH unless E
1
and E
2
are LOW and E
3
is
HIGH. This multiple enable function allows easy parallel ex-
Inputs
E
1
H
X
X
L
L
L
L
L
L
L
L
E
2
X
H
X
L
L
L
L
L
L
L
L
E
3
X
X
L
H
H
H
H
H
H
H
H
A
0
X
X
X
L
H
L
H
L
H
L
H
A
1
X
X
X
L
L
H
H
L
L
H
H
A
2
X
X
X
L
L
L
L
H
H
H
H
O
0
H
H
H
L
H
H
H
H
H
H
H
O
1
H
H
H
H
L
H
H
H
H
H
H
O
2
H
H
H
H
H
L
H
H
H
H
H
pansion of the device to a 1-of-32 (5 lines to 32 lines) de-
coder with just four FCT138 devices and one inverter (see
Figure 1).
The FCT138 can be used as an 8-output demulti-
plexer by using one of the active LOW Enable inputs as the
data input and the other Enable inputs as strobes. The En-
able inputs which are not used must be permanently tied to
their appropriate active-HIGH or active-LOW state.
Outputs
O
3
H
H
H
H
H
H
L
H
H
H
H
O
4
H
H
H
H
H
H
H
L
H
H
H
O
5
H
H
H
H
H
H
H
H
L
H
H
O
6
H
H
H
H
H
H
H
H
H
L
H
O
7
H
H
H
H
H
H
H
H
H
H
L
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Logic Diagram
DS100963-4
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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2
Logic Diagram
(Continued)
54FCT138
3
DS100963-5
FIGURE 1. Expansion to 1-of-32 Decoding
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54FCT138
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Storage Temperature
Ambient Temperature under Bias
Junction Temperature under Bias
Ceramic
V
CC
Pin Potential to
Ground Pin
Input Voltage (Note 1)
Input Current (Note 1)
Voltage Applied to Any Output
in the Disabled or
Power-Off State
in the HIGH State
Current Applied to Output
−65˚C to +150˚C
−55˚C to +125˚C
−55˚C to +175˚C
−0.5V to +7.0V
−0.5V to +7.0V
−30 mA to +5.0 mA
in LOW State (Max)
DC Latchup Source Current
Twice the rated I
OL
(mA)
−500 mA
Recommended Operating
Conditions
Free Air Ambient Temperature
Military
Supply Voltage
Military
Minimum Input Edge Rate
Data Input
Enable Input
−55˚C to +125˚C
+4.5V to +5.5V
(∆V/∆t)
50 mV/ns
20 mV/ns
−0.5V to +5.5V
−0.5V to V
CC
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 ’FCT Family Devices
Symbol
V
IH
V
IL
V
CD
V
OH
Parameter
Input HIGH Voltage
Input LOW Voltage
Input Clamp Diode Voltage
Output HIGH
Voltage
Output LOW
Voltage
Input HIGH Current
Input LOW Current
Output Short-Circuit Current
Quiescent Power Supply Current
Quiescent Power
Supply Current
Dynamic I
CC
54FCT
54FCT
V
OL
54FCT
54FCT
I
IH
I
IL
I
OS
I
CCQ
∆I
CC
I
CCD
4.3
2.4
0.2
0.5
5
−5
-60
1.5
2.0
0.4
µA
µA
mA
mA
mA
mA/
MHz
Max
Max
Max
Max
Max
Max
V
Min
FCT138
Min
2.0
0.8
−1.2
Max
V
V
V
V
Min
Min
Recognized HIGH Signal
Recognized LOW Signal
I
IN
= −18 mA
I
OH
= −300 µA
I
OH
= −12 mA
I
OL
= 300 µA
I
OL
= 32 mA
V
IN
= V
CC
V
IN
= 0.0V
V
OUT
= 0.0V
V
IN
<
0.2V or V
IN
5.3V, V
CC
=
5.5V
V
I
= 3.4V, V
CC
= 5.5V
Outputs Open, V
CC
= 5.5V, V
IN
5.3V or V
IN
<
0.2V, One Bit
Toggling, 50% Duty Cycle, OE =
GND, LE = V
CC
Outputs Open, f
CP
= 10 MHz,
V
CC
= 5.5V, V
IN
5.3V or V
IN
<
0.2V, One Bit Toggling, 50%
Duty Cycle, OE = GND, LE =
V
CC
Units
V
CC
Conditions
I
CCT
Total Power Supply
Current
5.5
mA
Max
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.
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4
54FCT138
AC Electrical Characteristics
V
CC
Symbol
Parameter
(V)
(Note 4)
Min
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
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 4:
Voltage Range 5.0 is 5.0V
±
0.5V
54FCT
T
A
= −55˚C
to +125˚C
C
L
= 50 pF
Max
12.0
12.0
12.5
12.5
12.5
12.5
ns
ns
ns
ns
ns
ns
1.0
1.0
1.0
1.0
1.0
1.0
Units
Fig.
No.
5.0
5.0
5.0
5.0
5.0
5.0
Capacitance
Symbol
C
IN
C
PD
Parameter
Input Capacitance
Power Dissipation
Capacitance
Typ
4.5
60.0
Units
pF
pF
Conditions
V
CC
= OPEN
V
CC
= 5.0V
5
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