© 1999 Fairchild Semiconductor Corporation

DS500058

www.fairchildsemi.com

September 1997

Revised December 1999

FST3253

Dual 4:1 Multiplexer/Demultiplexer Bus Switch

General Description

The Fairchild Switch FST3253 is a dual 4:1 high-speed

CMOS

TTL-compatible

multiplexer/demultiplexer

bus

switch. The low on resistance of the switch allows inputs to

be connected to outputs without adding propagation delay

or generating additional ground bounce noise.

selected B Port output. When OE is HIGH, the switch is

OPEN and a high-impedance state exists between the two

ports.

Features

■ 4

Ω switch connection between two ports.

■ Minimal propagation delay through the switch.

■ Zero bounce in flow-through mode.

■ Control inputs compatible with TTL level.

Ordering Code:

Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.

Logic Diagram

Pin Descriptions

Connection Diagram

Truth Table

Order Number

Package Number

Package Description

FST3253M

M16A

16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow

FST3253QSC

MQA16

16-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150 Wide

FST3253MTC

MTC16

16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

Pin Name

Description

Bus Switch Enables

Select Inputs

ABus A

Bus B

Function

X

X

H

X

Disconnect 1A

X

X

X

H

Disconnect 2A

L

LLL

A

= B

1

LH

L

L

A

= B

2

H

LLL

A

= B

3

HH

L

L

A

= B

4