MC74HC257 View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

MFG CO.

MC74HC257

Quad 2-Input Data Selector/Multiplexer with 3-State Outputs

Motorola => Freescale 

MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

Quad 2-Input Data

Selector/Multiplexer with

3-State Outputs

High–Performance Silicon–Gate CMOS

The MC74HC257 is identical in pinout to the LS257. The device inputs are

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

compatible with LSTTL outputs.

This device selects a (4–bit) nibble from either the A or B inputs as

determined by the Select input. The nibble is presented at the outputs in

noninverted form when the Output Enable pin is at a low level. A high level on

the Output Enable pin switches the outputs into the high–impedance state.

The HC257 is similar in function to the HC157 which do not have 3–state

outputs.

• Output Drive Capability: 15 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: 108 FETs or 27 Equivalent Gates

LOGIC DIAGRAM

NIBBLE

A INPUT

NIBBLE

B INPUT

A0 2

A1 5

A2 11

A3 14

B0 3

B1 6

B2 10

B3 13

4 Y0

7 Y1 NONINVERTING

9

Y2

NIBBLE

OUTPUT

12 Y3

SELECT 1

OUTPUT 15

ENABLE

PIN 16 = VCC

PIN 8 = GND

MC74HC257

16

1

N SUFFIX

PLASTIC PACKAGE

CASE 648–08

16

1

D SUFFIX

SOIC PACKAGE

CASE 751B–05

ORDERING INFORMATION

MC74HCXXXN

MC74HCXXXD

Plastic

SOIC

PIN ASSIGNMENT

SELECT 1

A0 2

B0 3

16 VCC

15

OUTPUT

ENABLE

14 A3

Y0 4

A1 5

13 B3

12 Y3

B1 6

Y1 7

11 A2

10 B2

GND 8

9 Y2

FUNCTION TABLE

Inputs

Output

Enable Select

Outputs

Y0 – Y3

H

X

Z

L

L

A0 – A3

L

H

B0 – B3

X = don’t care

Z = high impedance

A0 – A3, B0 – B3 = the levels of the

respective Nibble Inputs.

10/95

© Motorola, Inc. 1995

1

REV 6

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