TL/F/9478
54F/74F138 1-of-8 Decoder/Demultiplexer
November 1994
54F/74F138
1-of-8 Decoder/Demultiplexer
General Description
The ’F138 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 ’F138 devices or a 1-of-32 decoder using four ’F138
devices and one inverter.
Features
YDemultiplexing capability
YMultiple input enable for easy expansion
YActive LOW mutually exclusive outputs
YGuaranteed 4000V minimum ESD protection
Commercial Military Package Package Description
Number
74F138PC N16E 16-Lead (0.300×Wide) Molded Dual-In-Line
54F138DM (Note 2) J16A 16-Lead Ceramic Dual-In-Line
74F138SC (Note 1) M16A 16-Lead (0.150×Wide) Molded Small Outline, JEDEC
74F138SJ (Note 1) M16D 16-Lead (0.300×Wide) Molded Small Outline, EIAJ
54F138FM (Note 2) W16A 16-Lead Cerpack
54F138LM (Note 2) E20A 20-Lead Ceramic Leadless Chip Carrier, Type C
Note 1: Devices also available in 13×reel. Use suffix eSCX and SJX.
Note 2: Military grade device with environmental and burn-in processing. Use suffix eDMQB, FMQB and LMQB.
Logic Symbols
TL/F/9478–3
IEEE/IEC
TL/F/9478–6
Connection Diagrams
Pin Assignment for DIP,
SOIC and Flatpak
TL/F/9478–1
Pin Assignment
for LCC
TL/F/9478–2
TRI-STATEÉis a registered trademark of National Semiconductor Corporation.
C1995 National Semiconductor Corporation RRD-B30M75/Printed in U. S. A.
Unit Loading/Fan Out
54F/74F
Pin Names Description U.L. Input IIH/IIL
HIGH/LOW Output IOH/IOL
A0–A2Address Inputs 1.0/1.0 20 mA/b0.6 mA
E1,E
2Enable Inputs (Active LOW) 1.0/1.0 20 mA/b0.6 mA
E3Enable Input (Active HIGH) 1.0/1.0 20 mA/b0.6 mA
O0–O7Outputs (Active LOW) 50/33.3 b1 mA/20 mA
Functional Description
The ’F138 high-speed 1-of-8 decoder/demultiplexer ac-
cepts three binary weighted inputs (A0, A1, A2) and, when
enabled, provides eight mutually exclusive active LOW out-
puts (O0–O7). The ’F138 features three Enable inputs, two
active LOW (E1, E2) and one active HIGH (E3). All outputs
will be HIGH unless E1and E2are LOW and E3is HIGH.
This multiple enable function allows easy parallel expansion
of the device to a 1-of-32 (5 lines to 32 lines) decoder with
just four ’F138 devices and one inverter (See
Figure 1
). The
’F138 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
E1E2E3A0A1A2O0O1O2O3O4O5O6O7
HXXXXXHH H HHHHH
XHXXXXHH H HHHHH
XXLXXXHH H HHHHH
LLHL L L L H H HHHHH
LLHHL LHL H HHHHH
LLHLHLHH L HHHHH
LLHHHLHH H L HHHH
LLHL LHHH H HL HHH
LLHHLHHHHHHLHH
LLHLHHHH H HHH LH
LLHHHHHH H HHHHL
H
e
HIGH Voltage Level
LeLOW Voltage Level
XeImmaterial
2
Logic Diagram
TL/F/9478–4
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
3
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 b65§Ctoa
150§C
Ambient Temperature under Bias b55§Ctoa
125§C
Junction Temperature under Bias b55§Ctoa
175§C
Plastic b55§Ctoa
150§C
VCC Pin Potential to
Ground Pin b0.5V to a7.0V
Input Voltage (Note 2) b0.5V to a7.0V
Input Current (Note 2) b30 mA to a5.0 mA
Voltage Applied to Output
in HIGH State (with VCC e0V)
Standard Output b0.5V to VCC
TRI-STATEÉOutput b0.5V to a5.5V
Current Applied to Output
in LOW State (Max) twice the rated IOL (mA)
ESD Last Passing Voltage (Min) 4000V
Note 1: Absolute maximum ratings are values beyond which the device may
be damaged or have its useful life impaired. Functional operation under
these conditions is not implied.
Note 2: Either voltage limit or current limit is sufficient to protect inputs.
Recommended Operating
Conditions
Free Air Ambient Temperature
Military b55§Ctoa
125§C
Commercial 0§Ctoa
70§C
Supply Voltage
Military a4.5V to a5.5V
Commercial a4.5V to a5.5V
DC Electrical Characteristics
Symbol Parameter 54F/74F Units VCC Conditions
Min Typ Max
VIH Input HIGH Voltage 2.0 V Recognized as a HIGH Signal
VIL Input LOW Voltage 0.8 V Recognized as a LOW Signal
VCD Input Clamp Diode Voltage b1.2 V Min IIN eb
18 mA
VOH Output HIGH 54F 10% VCC 2.5 IOH eb
1mA
Voltage 74F 10% VCC 2.5 V Min IOH eb
1mA
74F 5% VCC 2.7 IOH eb
1mA
V
OL Output LOW 54F 10% VCC 0.5 V Min IOL e20 mA
Voltage 74F 10% VCC 0.5 IOL e20 mA
IIH Input HIGH 54F 20.0
mA Max VIN e2.7V
Current 74F 5.0
IBVI Input HIGH Current 54F 100
mA Max VIN e7.0V
Breakdown Test 74F 7.0
ICEX Output HIGH 54F 250
mA Max VOUT eVCC
Leakage Current 74F 50
VID Input Leakage 74F 4.75 V 0.0 IID e1.9 mA
Test All Other Pins Grounded
IOD Output Leakage 74F 3.75 mA 0.0 VIOD e150 mV
Circuit Current All Other Pins Grounded
IIL Input LOW Current b0.6 mA Max VIN e0.5V
IOS Output Short-Circuit Current b60 b150 mA Max VOUT e0V
ICCH Power Supply Current 13 20 mA Max VOeHIGH
ICCL Power Supply Current 13 20 mA Max VOeLOW
4
AC Electrical Characteristics
74F 54F 74F
TAea
25§CTA,V
CC eMil TA,V
CC eCom Fig.
Symbol Parameter VCC ea
5.0V CLe50 pF CLe50 pF Units No.
CLe50 pF
Min Typ Max Min Max Min Max
tPLH Propagation Delay 3.5 5.6 7.5 3.0 12.0 3.5 8.5 ns F–3
tPHL Anto On4.0 6.1 8.0 4.0 9.5 4.0 9.0
tPLH Propagation Delay 3.5 5.4 7.0 3.0 11.0 3.5 8.0 ns F–4
tPHL E1or E2to On3.0 5.3 7.0 3.0 8.0 3.0 7.5
tPLH Propagation Delay 4.0 6.2 8.0 3.5 12.5 4.0 9.0 ns F–4
tPHL E3to On3.5 5.6 7.5 3.5 8.5 3.5 8.5
TL/F/9478–5
FIGURE 1. Expansion to 1-of-32 Decoding
Ordering Information
The device number is used to form part of a simplified purchasing code where the package type and temperature range are
defined as follows:
74F 138 S C X
Temperature Range Family Special Variations
74FeCommercial QB eMilitary grade device with
54FeMilitary environmental and burn-in
processing
Device Type XeDevices shipped in 13×reel
Package Code Temperature Range
PePlastic DIP CeCommercial (0§Ctoa
70§C)
DeCeramic DIP MeMilitary (b55§Ctoa
125§C)
FeFlatpak
LeLeadless Chip Carrier (LCC)
SeSmall Outline SOIC JEDEC
SJ eSmall Outline SOIC EIAJ
5
6
Physical Dimensions inches (millimeters)
20-Lead Ceramic Leadless Chip Carrier (L)
NS Package Number E20A
7
Physical Dimensions inches (millimeters) (Continued)
16-Lead Ceramic Dual-In-Line Package (D)
NS Package Number J16A
16-Lead (0.150×Wide) Molded Small Outline Package, JEDEC (S)
NS Package Number M16A
8
Physical Dimensions inches (millimeters) (Continued)
16-Lead (0.300×Wide) Molded Small Outline Package, EIAJ (SJ)
NS Package Number M16D
16-Lead (0.300×Wide) Molded Dual-In-Line Package (P)
NS Package Number N16E
9
54F/74F138 1-of-8 Decoder/Demultiplexer
Physical Dimensions inches (millimeters) (Continued)
16-Lead Ceramic Flatpak (F)
NS Package Number W16A
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