Rev.3.00, Jul.15.2005, page 1 of 5

HD74LS251

1 of 8 Data Selector / Multiplexer

(with strobe and three-state outputs)

REJ03D0467–0300

Rev.3.00

Jul.15.2005

This data selector / multiplexer contains full on-chip binary decoding to select one-of-eight data sources and features a

strobe-controlled 3-state output.

The strobe must be at a low logic level to enable this device. The 3-state outputs permit a number of outputs to be

connected to a common bus.

When the strobe input is high, both outputs are in a high-impedance state in which both the upper and lower transistors

of each totem-pole output are off, and the output neither drives nor loads the bus significantly. When the strobe is low,

the outputs are activated and operate as standard TTL totem-pole outputs.

To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output

control circuitry is designed so that the average output disable time is shorter than the average output enable time.

Features

• Ordering Information

Part Name

Package Type

Package Code

(Previous Code)

Package

Abbreviation

Taping Abbreviation

(Quantity)

HD74LS251P

DILP-16 pin

PRDP0016AE-B

(DP-16FV)

P

—

HD74LS251FPEL

SOP-16 pin (JEITA)

PRSP0016DH-B

(FP-16DAV)

FP

EL (2,000 pcs/reel)

Note:

Please consult the sales office for the above package availability.

Pin Arrangement

(Top view)

3

GND

15

16

1

2

3

4

5

6

7

14

8

9

10

11

12

13

S

C

W

B

A

2

1

0

Y

W

Strobe

C

B

A

7

6

5

4

Y

Data Inputs

Data Select

Data Inputs

Outputs