IN74HC251A

1

WITH

High-Performance Silicon-Gate CMOS

The IN74HC251 is identical in pinout to the LS/ALS251. The

device inputs are compatible with standard CMOS outputs; with

pullup resistors, they are compatible with LS/ALSTTL outputs.

The device selects one of the eight binary Data Inputs, as

determined by the Address Inputs. The Output Enable pin must

be at a low level for the selected data to appear at the outputs. If

Output Enable is high, the Y and the Y outputs are in the high-

impedance state. This 3-State feature allows the IN74HC251 to

be used in bus-oriented systems.

• Outputs Directly Interface to CMOS, NMOS, and TTL

• Operating Voltage Range: 2.0 to 6.0 V

• Low Input Current: 1.0 µA

• High Noise Immunity Characteristic of CMOS Devices

ORDERING INFORMATION

IN74HC251N Plastic

IN74HC251D SOIC

packages

FUNCTION TABLE

Inputs

Outputs

A2 A1

A0

OE

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

D0,D1...D7=the level of the

respective D input

Z = high-impedance state

X = don’t care

LOGIC DIAGRAM

PIN 8 = GND

PIN ASSIGNMENT