M74HC643

2/11

INPUT AND OUTPUT EQUIVALENT CIRCUIT

PIN DESCRIPTION

TRUTH TABLE

X : Don’t Care

Z : High Impedance

LOGIC DIAGRAM

This logic diagram has not be used to estimate propagation delays

PIN No

SYMBOL

NAME AND FUNCTION

1

DIR

Directional Control

2, 3, 4, 5, 6,

7, 8, 9

A1 to A8

Data Inputs/Outputs

18, 17, 16,

15, 14, 13,

12, 11

B1 to B8

Data Inputs/Outputs

19

G

Output Enable Input

10

GND

Ground (0V)

20

Positive Supply Voltage

INPUTS

FUNCTION

OUTPUT

G

DIR

A BUS

B BUS

Yn

L

L

OUTPUT

INPUT

A = B

L

H

INPUT

OUTPUT

B = A

HX

Z

Z

Z