SLS SL74LS138N

SL74LS138
3-to-8-Line
Decoder/Demultiplexer
This schottky-clamped TTL MSI circuit is designed to be used in
high-performance memory-decording or data-routing applications
requiring very short propagation delay time. In high-performance
memory systems this decode can be used to minimize the effects of
system decoding. When employed with high-speed memories utilizing
a fast enable circuit the delay times of this decorder and the enable time
of the memory are usually less than the typical access times of the
memory. This means that the effective system delay introduced by the
schottky-clampled system decoder is negligible.
• Designed Specifically for High Speed Memory Decoders and Data
Transmission Systems
• Incorporate 3 Enabler Inputs to Simplify Cascading AND/OR Data
Reception
• Schottky Clamped for High Performance
ORDERING INFORMATION
SL74LS138N Plastic
SL74LS138D SOIC
TA = 0° to 70° C
for all packages
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Inputs
PIN 16 =VCC
PIN 8 = GND
Outputs
CS1 CS2 CS3
A2 A1 A0
Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
X X H
X H X
L X X
X X X
X X X
X X X
H H H H H H H H
H H H H H H H H
H H H H H H H H
H
H
H
H
L
L
L
L
L
L
L
L
L L L
L L H
L H L
L H H
L
H
H
H
H
L
H
H
H
H
L
H
H
H
H
L
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
H L L
H L H
H H L
H H H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L H H H
H L H H
H H L H
H H H L
H = high level (steady state)
L = low level (steady state)
X = don’t care
SLS
System Logic
Semiconductor
H
H
H
H
H
H
H
H
H
H
H
H
SL74LS138
MAXIMUM RATINGS *
Symbol
Parameter
Value
Unit
VCC
Supply Voltage
7.0
V
VIN
Input Voltage
7.0
V
VOUT
Output Voltage
5.5
V
Tstg
Storage Temperature Range
-65 to +150
°C
*
Maximum Ratings are those values beyond which damage to the device may occur.
Functional operation should be restricted to the Recommended Operating Conditions.
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Min
Max
Unit
5.25
V
VCC
Supply Voltage
4.75
VIH
High Level Input Voltage
2.0
VIL
Low Level Input Voltage
0.8
V
IOH
High Level Output Current
-0.4
mA
IOL
Low Level Output Current
8.0
mA
TA
Ambient Temperature Range
+70
°C
0
V
DC ELECTRICAL CHARACTERISTICS over full operating conditions
Guaranteed Limit
Symbol
Parameter
Test Conditions
Min
Max
Unit
-1.5
V
VIK
Input Clamp Voltage
VCC = min, IIN = -18 mA
VOH
High Level Output Voltage
VCC = min, IOH = -0.4 mA
VOL
Low Level Output Voltage
VCC = min, IOL = 4 mA
0.4
VCC = min, IOL = 8 mA
0.5
VCC = max, VIN = 2.7 V
20
µA
VCC = max, VIN = 7.0 V
0.1
mA
-0.4
mA
-100
mA
10
mA
IIH
High Level Input Current
IIL
Low Level Input Current
VCC = max, VIN = 0.4 V
IO
Output Short Circuit Current
VCC = max, VO = 0 V
(Note 1)
ICC
Supply Current
VCC = max
Outputs enabled and open
2.7
-20
V
V
Note 1: Not more than one output should be shorted at a time, and duration should not exceed one second.
SLS
System Logic
Semiconductor
SL74LS138
AC ELECTRICAL CHARACTERISTICS (TA=25°C, VCC = 5.0 V, CL = 15 pF, RL = 2 kΩ, t r =15
ns, tf = 6.0 ns)
Symbol
tPLH
Parameter
Level
Maximum Propagation Delay, Input A to
Output Y
tPHL
Maximum Propagation Delay, Input A to
Output Y
tPLH
Maximum Propagation Delay, Input A to
Output Y
tPHL
Maximum Propagation Delay, Input A to
Output Y
tPLH
Maximum Propagation Delay , CS1 to
Output Y
Unit
20
ns
41
ns
27
ns
39
ns
26
ns
38
ns
18
ns
32
ns
3
3
Maximum Propagation Delay , CS1 to
Output Y
tPLH
Maximum Output Transition Time , CS2 or CS3
to Output Y
Maximum Output Transition Time , CS2 or CS3
to Output Y
Figure 1. Switching Waveforms
Max
2
tPHL
tPHL
Min
2
Figure 2. Switching Waveforms
NOTES A. CL includes probe and jig capacitance.
B. All diodes are 1N916 or 1N3064.
Figure 3. Switching Waveforms
SLS
System Logic
Semiconductor
Figure 4. Test Circuit