SN74LS42

http://onsemi.com

3

FUNCTIONAL DESCRIPTION

The LS42 decoder accepts four active HIGH BCD inputs

and provides ten mutually exclusive active LOW outputs, as

shown by logic symbol or diagram. The active LOW outputs

facilitate addressing other MSI units with LOW input

enables.

The logic design of the LS42 ensures that all outputs

are HIGH when binary codes greater than nine are applied

to the inputs.

function when the LS42 is used as a one-of-eight decoder.

demultiplexer application.

TRUTH TABLE

0

1

2

3

4

5

6

7

8

9

L

H

L

H

L

H

L

H

L

H

L

H

L

H

L

H

L

L

H

H

L

L

H

H

L

L

H

H

L

L

H

H

L

L

L

L

H

H

H

H

L

L

L

L

H

H

H

H

L

L

L

L

L

L

L

L

H

H

H

H

H

H

H

H

L

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

H

H

H

H

H

H

H

H

L

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

H

H

H

H

H

H

H

H

L

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

H

H

H

H

H

H

H

H

L

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

H

H

H

H

H

H

H

H

L

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

L

H

H

H

H

H

H

H = HIGH Voltage Level

L = LOW Voltage Level