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
nDemultiplexing capability
nMultiple input enable for easy expansion
nActive LOW mutually exclusive outputs
nOutputs sink capability of 32mA, source capability of
12mA
nTTL input and output level compatible
nCMOS power consumption
nStandard Microcircuit Drawing (SMD) 5962-8765401
Ordering Code
Military Package Package Description
Number
54FCT138DMQB J16A 16-Lead Ceramic Dual-In-Line
54FCT138FMQB W16A 16-Lead Cerpack
54FCT138LMQB E20A 20-Lead Ceramic Leadless Chip Carrier, Type C
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.
DS100963-1
IEEE/IEC
DS100963-7
Pin Assignment
for DIP and Flatpak
DS100963-2
Pin Assignment
for LCC
DS100963-3
October 1999
54FCT138 1-of-8 Decoder/Demultiplexer
© 1999 National Semiconductor Corporation DS100963 www.national.com
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-
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.
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
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.
54FCT138
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Logic Diagram (Continued)
DS100963-5
FIGURE 1. Expansion to 1-of-32 Decoding
54FCT138
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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.
Storage Temperature −65˚C to +150˚C
Ambient Temperature under Bias −55˚C to +125˚C
Junction Temperature under Bias
Ceramic −55˚C to +175˚C
V
CC
Pin Potential to
Ground Pin −0.5V to +7.0V
Input Voltage (Note 1) −0.5V to +7.0V
Input Current (Note 1) −30 mA to +5.0 mA
Voltage Applied to Any Output
in the Disabled or
Power-Off State −0.5V to +5.5V
in the HIGH State −0.5V to V
CC
Current Applied to Output
in LOW State (Max) Twice the rated I
OL
(mA)
DC Latchup Source Current −500 mA
Recommended Operating
Conditions
Free Air Ambient Temperature
Military −55˚C to +125˚C
Supply Voltage
Military +4.5V to +5.5V
Minimum Input Edge Rate (∆V/∆t)
Data Input 50 mV/ns
Enable Input 20 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 ’FCT Family Devices
Symbol Parameter FCT138 Units V
CC
Conditions
Min Max
V
IH
Input HIGH Voltage 2.0 V Recognized HIGH Signal
V
IL
Input LOW Voltage 0.8 V Recognized LOW Signal
V
CD
Input Clamp Diode Voltage −1.2 V Min I
IN
=−18 mA
V
OH
Output HIGH
Voltage 54FCT 4.3 V Min I
OH
=−300 µA
54FCT 2.4 I
OH
=−12 mA
V
OL
Output LOW
Voltage 54FCT 0.2 V Min I
OL
=300 µA
54FCT 0.5 I
OL
=32 mA
I
IH
Input HIGH Current 5 µA Max V
IN
=V
CC
I
IL
Input LOW Current −5 µA Max V
IN
=0.0V
I
OS
Output Short-Circuit Current -60 mA Max V
OUT
=0.0V
I
CCQ
Quiescent Power Supply Current 1.5 mA Max V
IN
<0.2V or V
IN
5.3V, V
CC
=
5.5V
∆I
CC
Quiescent Power
Supply Current 2.0 mA Max V
I
=3.4V, V
CC
= 5.5V
I
CCD
Dynamic I
CC
0.4 mA/
MHz Max 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
I
CCT
Total Power Supply
Current 5.5 mA Max 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
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.
54FCT138
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AC Electrical Characteristics
54FCT
V
CC
T
A
=−55˚C Fig.
Symbol Parameter (V) to +125˚C Units No.
(Note 4) C
L
=50 pF
Min Max
t
PLH
Propagation Delay 5.0 1.0 12.0 ns
A
n
to O
n
t
PHL
Propagation Delay 5.0 1.0 12.0 ns
A
n
to O
n
t
PLH
Propagation Delay 5.0 1.0 12.5 ns
E
1
or E
2
to O
n
t
PHL
Propagation Delay 5.0 1.0 12.5 ns
E
1
or E
2
to O
n
t
PLH
Propagation Delay 5.0 1.0 12.5 ns
E
3
toOn
t
PHL
Propagation Delay 5.0 1.0 12.5 ns
E
3
toOn
Note 4: 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
54FCT138
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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
54FCT138
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
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whose failure to perform when properly used in
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can be reasonably expected to cause the failure of
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www.national.com
16 Lead Ceramic Flatpak (F)
NS Package Number W16A
54FCT138 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.
