MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

1

REV 6

10/95

8-Input Data Selector/

Multiplexer with

3-State Outputs

High–Performance Silicon–Gate CMOS

The MC54/74HC251 is identical in pinout to the LS251. The device inputs

are compatible with standard CMOS outputs; with pullup resistors, they are

compatible with LSTTL outputs.

This device selects one of the eight binary Data Inputs, as determined by

the Address Inputs. The Output Enable pin must be a low level for the

selected data to appear at the outputs. If Output Enable is high, both the Y

and the Y outputs are in the high–impedance state. This 3–state feature

allows the HC251 to be used in bus–oriented systems.

The HC251 is similar in function to the HC151 which does not have

3–state outputs.

• Output Drive Capability: 10 LSTTL Loads

• Outputs Directly Interface to CMOS, NMOS, and TTL

• Operating Voltage Range: 2 to 6 V

• Low Input Current: 1 µA

• High Noise Immunity Characteristic of CMOS Devices

• In Compliance with the Requirements Defined by JEDEC Standard

No. 7A

• Chip Complexity: 134 FETs or 33.5 Equivalent Gates

LOGIC DIAGRAM

D0

D1

D2

D3

D4

D5

D6

D7

A0

A1

A2

OUTPUT ENABLE

Y

Y

DATA

OUTPUTS

DATA

INPUTS

ADDRESS

INPUTS

5

6

4

3

2

1

15

14

13

12

11

10

9

7

PIN 16 = VCC

PIN 8 = GND

MC54/74HC251

PIN ASSIGNMENT

FUNCTION TABLE

Inputs

Outputs

Output

A2

A1

A0

Enable

Y

Y

X

X

X

H

Z

Z

L

L

L

L

D0

D0

L

L

H

L

D1

D1

L

H

L

L

D2

D2

L

H

H

L

D3

D3

H

L

L

L

D4

D4

H

L

H

L

D5

D5

H

H

L

L

D6

D6

H

H

H

L

D7

D7

Z = high impedance

D0, D1,

…, D7 = the level of the respective

D input.

13

14

15

16

9

10

11

12

5

4

3

2

1

8

7

6

D7

D6

D5

D4

VCC

A2

A1

A0

D0

D1

D2

D3

GND

OUTPUT

ENABLE

Y

Y

D SUFFIX

SOIC PACKAGE

CASE 751B–05

N SUFFIX

PLASTIC PACKAGE

CASE 648–08

ORDERING INFORMATION

MC54HCXXXJ

MC74HCXXXN

MC74HCXXXD

Ceramic

Plastic

SOIC

1

16

1

16

J SUFFIX

CERAMIC PACKAGE

CASE 620–10

1

16