MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

1

REV 6

10/95

1-of-8 Decoder/Demultiplexer

High–Performance Silicon–Gate CMOS

The MC54/74HC138A is identical in pinout to the LS138. The device

inputs are compatible with standard CMOS outputs; with pullup resistors,

they are compatible with LSTTL outputs.

The HC138A 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–select-

ing 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.

• Output Drive Capability: 10 LSTTL Loads

• Outputs Directly Interface to CMOS, NMOS and TTL

• Operating Voltage Range: 2.0 to 6.0 V

• High Noise Immunity Characteristic of CMOS Devices

• In Compliance with the Requirements Defined by JEDEC Standard

No. 7A

• Chip Complexity: 100 FETs or 29 Equivalent Gates

LOGIC DIAGRAM

7

Y6

Y5

Y4

Y3

Y2

Y1

Y0

Y7

9

10

11

12

13

14

15

3

2

1

CS1

CS2

A0

A1

A2

ACTIVE–LOW

OUTPUTS

ADDRESS

INPUTS

CS3

CHIP–

SELECT

INPUTS

5

4

6

PIN 16 = VCC

PIN 8 = GND

Inputs

Outputs

CS1CS2 CS3 A2 A1 A0 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7

X

X

H

X

X

X

H

H

H

H

H

H

H

H

X

H

X

X

X

X

H

H

H

H

H

H

H

H

L

X

X

X

X

X

H

H

H

H

H

H

H

H

H

L

L

L

L

L

L

H

H

H

H

H

H

H

H

L

L

L

L

H

H

L

H

H

H

H

H

H

H

L

L

L

H

L

H

H

L

H

H

H

H

H

H

L

L

L

H

H

H

H

H

L

H

H

H

H

H

L

L

H

L

L

H

H

H

H

L

H

H

H

H

L

L

H

L

H

H

H

H

H

H

L

H

H

H

L

L

H

H

L

H

H

H

H

H

H

L

H

H

L

L

H

H

H

H

H

H

H

H

H

H

L

FUNCTION TABLE

H = high level (steady state); L = low level (steady state);

X = don’t care

MC54/74HC138A

PIN ASSIGNMENT

13

14

15

16

9

10

11

12

5

4

3

2

1

8

7

6

A0

CS2

A2

A1

Y7

CS1

CS3

GND

Y3

Y2

Y1

Y0

VCC

Y5

Y4

Y6

D SUFFIX

SOIC PACKAGE

CASE 751B–05

N SUFFIX

PLASTIC PACKAGE

CASE 648–08

ORDERING INFORMATION

MC54HCXXXAJ

MC74HCXXXAN

MC74HCXXXAD

MC74HCXXXADT

Ceramic

Plastic

SOIC

TSSOP

1

16

1

16

1

16

DT SUFFIX

TSSOP PACKAGE

CASE 948F–01

J SUFFIX

CERAMIC PACKAGE

CASE 620–10

1

16