1

Data sheet acquired from Harris Semiconductor

SCHS171

Features

• Buffered Inputs

• Typical Propagation Delay ( In to Output ) = 12ns at

• Fanout (Over Temperature Range)

- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads

- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads

• Balanced Propagation Delay and Transition Times

• Significant Power Reduction Compared to LSTTL

Logic ICs

• HC Types

- 2V to 6V Operation

• HCT Types

- 4.5V to 5.5V Operation

- Direct LSTTL Input Logic Compatibility,

Description

The Harris CD74HC257 and CD74HCT257 are quad 2-input

multiplexers which select four bits of data from two sources

under the control of a common Select Input (S). The Output

Enable input (OE) is active LOW. When OE is HIGH, all of

the outputs (1Y-4Y) are in the high impedance state regard-

less of all other input conditions.

Moving data from two groups of registers to four common

output busses is a common use of the 257. The state of the

Select input determines the particular register from which

the data comes. It can also be used as a function generator.

Pinout

CD74HC257, CD74HC257

(PDIP, SOIC)

TOP VIEW

Ordering Information

PART NUMBER

TEMP. RANGE

PACKAGE

PKG.

NO.

CD74HC257E

-55 to 125

16 Ld PDIP

E16.3

CD74HCT257E

-55 to 125

16 Ld PDIP

E16.3

CD74HC257M

-55 to 125

16 Ld SOIC

M16.15

CD74HCT257M

-55 to 125

16 Ld SOIC

M16.15

NOTES:

1. When ordering, use the entire part number. Add the suffix 96 to

obtain the variant in the tape and reel.

2. Wafer or die for this part number is available which meets all

electrical specifications. Please contact your local sales office or

Harris customer service for ordering information.

14

15

16

9

13

12

11

10

1

2

3

4

5

7

6

8

S

1Y

GND

2Y

4Y

3Y

OE

November 1997

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures.

Copyright

CD74HC257,

CD74HCT257

High Speed CMOS Logic Quad 2-Input

Multiplexer with Three-State Non-Inverting Outputs

File Number

1650.1

[ /Title

(CD74

HC257

,

CD74

HCT25

7)

/Sub-

ject

(High

Speed

CMOS

Logic

Quad

2-Input

Multi-

plexer