2

Functional Diagrams

CD74HCT242

CD74HC243, CD74HC243

DIRECTION

SELECT LOGIC

A0

A1

A2

A3

OEB

OEA

3

4

5

6

1

13

11

10

9

8

B0

B1

B2

B3

DIRECTION

SELECT LOGIC

A0

A1

A2

A3

OEB

OEA

3

4

5

6

1

13

11

10

9

8

B0

B1

B2

B3

TRUTH TABLE

CONTROL INPUTS

HCT242 SERIES

HC, HCT243 SERIES

DATA PORT STATUS

DATA PORT STATUS

OEB

OEA

An

Bn

An

Bn

HH

OIOI

L

H

ZZZZ

H

L

ZZZZ

LL

I

OIO

NOTE:

H = High Voltage Level

L = Low Voltage Level

I = Input

O = Output (Same Level as Input)

O = Output (Inversion of Input Level)

Z = High Impedance

To prevent excess currents in the High Z modes all I/O terminals should be terminated with 10k

Ω to 1MΩ resistors.

CD74HCT242, CD74HC243, CD74HCT243