2

Functional Diagram

TRUTH TABLE

SELECT INPUTS

DATA INPUTS

ENABLE

INPUTS

OUTPUT

S1

S0

nI0

nI1

nI2

nI3

nOE

nY

XXXXXX

HZ

LLL

X

X

X

LL

L

L

H

XXX

L

H

LH

X

L

X

X

L

L

L

HXHX

X

L

H

HL

X

X

L

X

L

L

H

L

X

XHX

L

H

H

H

XXX

L

L

L

H

H

XXX

H

L

H

Select inputs S1 and S0 are common to both sections. H = High level, L = Low inputs, X = Don’t care, Z = High imped-

ance.

GND = 8

VCC = 16

1I2

4

3

1I3

1I1

5

1I0

6

1

14

2

2I2

12

13

2I3

2I1

11

2I0

10

15

1OE

S0

S1

2OE

SEL/MUX

SEL/MUX

9

7

1Y

2Y

CD74AC253, CD54/74ACT253