TECHNICAL DATA
IN74HC138A
1-of-8 Decoder/Demultiplexer
High-Performance Silicon-Gate CMOS
The IN74HC138A is identical in pinout to the LS/ALS138. The
device inputs are compatible with standard CMOS outputs; with pullup
resistors, they are compatible with LS/ALSTTL outputs.
The IN74HC138A decodes a three-bit Address to one-of-eight
active-low 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.
ORDERING INFORMATION
IN74HC138AN Plastic
IN74HC138AD SOIC
TA = -55° to 125° C for all packages
•
•
•
Outputs Directly Interface to CMOS, NMOS, and TTL
Operating Voltage Range: 2.0 to 6.0 V
Low Input Current: 1.0 µA
•
High Noise Immunity Characteristic of CMOS Devices
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Inputs
CS1CS2CS3
Outputs
A2 A1A0
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 L L
H L L
H L L
H L L
L L L
L L H
L H L
L 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
PIN 16 =VCC
PIN 8 = GND
H L L
H L L
H L L
H L L
H L L
H L H
H H L
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 = high level (steady state)
L = low level (steady state)
X = don’t care
141
INTEGRAL [ INTEGRAL CORP. ]
