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SN74LS138
1-of-8 Decoder/
Demultiplexer
The LSTTL / MSI SN74LS138 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 LS138
devices or to a 1-of-32 decoder using four LS138s and one inverter.
The LS138 is fabricated with the Schottky barrier diode process for
high speed and is completely compatible with all ON Semiconductor
TTL families.
• Demultiplexing Capability
• Multiple Input Enable for Easy Expansion
• Typical Power Dissipation of 32 mW
• Active Low Mutually Exclusive Outputs
• Input Clamp Diodes Limit High Speed Termination Effects
GUARANTEED OPERATING RANGES
Symbol
Parameter
Min Typ Max Unit
VCC Supply Voltage
TA Operating Ambient
Temperature Range
4.75 5.0 5.25
V
0 25 70 °C
IOH Output Current – High
IOL Output Current – Low
– 0.4
8.0
mA
mA
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LOW
POWER
SCHOTTKY
16
1
PLASTIC
N SUFFIX
CASE 648
16
1
SOIC
D SUFFIX
CASE 751B
ORDERING INFORMATION
Device
Package
Shipping
SN74LS138N 16 Pin DIP 2000 Units/Box
SN74LS138D
16 Pin
2500/Tape & Reel
© Semiconductor Components Industries, LLC, 1999
December, 1999 – Rev. 6
1
Publication Order Number:
SN74LS138/D
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SN74LS138
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Symbol
Parameter
Limits
Min Typ Max
Unit
Test Conditions
VIH Input HIGH Voltage
2.0
Guaranteed Input HIGH Voltage for
V All Inputs
VIL Input LOW Voltage
0.8
V
Guaranteed Input LOW Voltage for
All Inputs
VIK Input Clamp Diode Voltage
VOH Output HIGH Voltage
VOL Output LOW Voltage
– 0.65 – 1.5 V VCC = MIN, IIN = – 18 mA
2.7 3.5
V VCC = MIN, IOH = MAX, VIN = VIH
or VIL per Truth Table
0.25 0.4
0.35 0.5
V IOL = 4.0 mA
V IOL = 8.0 mA
VCC = VCC MIN,
VIN = VIL or VIH
per Truth Table
IIH Input HIGH Current
20 µA VCC = MAX, VIN = 2.7 V
0.1 mA VCC = MAX, VIN = 7.0 V
IIL Input LOW Current
– 0.4 mA VCC = MAX, VIN = 0.4 V
IOS
Short Circuit Current (Note 1)
– 20
–100 mA VCC = MAX
ICC Power Supply Current
10 mA VCC = MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS (TA = 25°C)
Symbol
tPLH
tPHL
tPLH
tPHL
tPLH
tPHL
tPLH
tPHL
Parameter
Propagation Delay
Address to Output
Propagation Delay
Address to Output
Propagation Delay E1 or E2
Enable to Output
Propagation Delay E3
Enable to Output
Levels of
Delay
2
2
3
3
2
2
3
3
Limits
Min Typ Max
13 20
27 41
18 27
26 39
12 18
21 32
17 26
25 38
Unit
ns
ns
ns
ns
Test Conditions
VCC = 5.0 V
CL = 15 pF
VIN
VOUT
1.3 V
tPHL
1.3 V
AC WAVEFORMS
1.3 V
tPLH
1.3 V
VIN
VOUT
1.3 V
tPHL tPLH
1.3 V
1.3 V
1.3 V
Figure 1.
Figure 2.
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