2

Functional Diagram

‘HC243, ‘HCT243

TRUTH TABLE

CONTROL INPUTS

HC, HCT243 SERIES

DATA PORT STATUS

OEB

OEA

An

Bn

HH

O

I

LH

Z

Z

HL

Z

Z

LL

I

O

H= High Voltage Level

L= Low Voltage Level

I= Input

O= Output (Same Level as Input)

Z= High Impedance

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

Ω

to 1M

Ω resistors.

DIRECTION

SELECT LOGIC

A0

A1

A2

A3

OEB

OEA

3

4

5

6

1

13

11

10

9

8

B0

B1

B2

B3

CD54HC243, CD74HC243, CD54HCT243, CD74HCT243