© 1999 Fairchild Semiconductor Corporation

DS500020

www.fairchildsemi.com

June 1997

Revised December 1999

FST3245

Octal Bus Switch

General Description

The Fairchild Switch FST3245 provides 8-bits of high-

speed CMOS TTL-compatible bus switching in a standard

’245 pin-out. The low on resistance of the switch allows

inputs to be connected to outputs without adding propaga-

tion delay or generating additional ground bounce noise.

The device is organized as an 8-bit switch. When OE is

LOW, the switch is ON and Port A is connected to Port B.

When OE is HIGH, the switch is OPEN and a high-imped-

ance state exists between the two ports.

Features

s 4

Ω switch connection between two ports.

s Minimal propagation delay through the switch.

s Zero bounce in flow-through mode.

s Control inputs compatible with TTL level.

Ordering Code:

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

Logic Diagram

Pin Descriptions

Connection Diagram

Truth Table

Order Number

Package Number

Package Description

FST3245WM

M20B

20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide

FST3245QSC

MQA20

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

FST3245MTC

MTC20

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

Pin Name

Description

OE

Bus Switch Enable

ABus A

BBus B

Input OE

Function

L

Connect

H

Disconnect