IN74ACT138

1

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

• 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

ORDERING INFORMATION

IN74ACT138N Plastic

IN74ACT138D SOIC

packages

PIN ASSIGNMENT

LOGIC DIAGRAM

PIN 8 = GND

FUNCTION TABLE

Inputs

Outputs

CS1CS2CS3

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

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