IN74ACT138
1-OF-8 DECODER/DEMULTIPLEXER
High-Speed Silicon-Gate CMOS
The IN74ACT138 is identical in pinout to the LS/ALS138,
HC/HCT138. The IN74ACT138 may be used as a level converter
for interfacing TTL or NMOS outputs to High Speed CMOS inputs.
The IN74ACT138 decodes a three-bit Address to one-of-eight
active-lot outputs. This device features three Chip Select inputs,
two active-low and one active-high to facilitate the demultiplexing,
cascading, and chip-selecting functions. The demultiplexing
function is accomplished by using the Address inputs to select the
desired device output; one of the Chip Selects is used as a data
input while the other Chip Selects are held in their active states.
• TTL/NMOS Compatible Input Levels
ORDERING INFORMATION
• Outputs Directly Interface to CMOS, NMOS, and TTL
• Operating Voltage Range: 4.5 to 5.5 V
• Low Input Current: 1.0 µA; 0.1 µA @ 25°C
• Outputs Source/Sink 24 mA
IN74ACT138N Plastic
IN74ACT138D SOIC
TA = -40° to 85° C for all
packages
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Inputs
CS1CS2CS3 A2 A1A0
Outputs
Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
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 H H H H H H H
H L H H H H H H
H H L H H H H H
H H H L H H H H
H H H H L H H H
H H H H H L H H
H H H H H H L H
H H H H H H H L
X X H
X H X
L X X
H L L
H L L
H L L
H L L
H L L
H L L
H L L
H L L
X X X
X X X
X X X
L L L
L L H
L H L
L H H
H L L
H L H
H H L
H H H
PIN 16 =VCC
PIN 8 = GND
H = high level (steady state)
L = low level (steady state)
X = don’t care
1
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