© 1999 Fairchild Semiconductor Corporation

DS500195

www.fairchildsemi.com

May 1999

Revised December 1999

FSTU3384

10-Bit Bus Switch with

−2V Undershoot Hardened Circuit (UHC) Protection

General Description

The Fairchild Switch FSTU3384 provides 10 bits of high-

speed CMOS TTL-compatible bus switches. The low on

resistance of the switch allows inputs to be connected to

outputs without adding propagation delay generating addi-

tional ground bounce noise. Both the A Ports and the B

Ports are “undershoot hardened” with UHC

 protection to

support an extended input range to 2.0V below ground.

Fairchild’s integrated Undershoot Hardened Circuit, UHC

senses undershoot at the I/Os, and responds by preventing

voltage differentials from developing and turning on the

switch. The device is organized as two 5-bit switches with

separate bus enable (OE) signals. 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-impedance state

exists between the two ports.

Features

s 4

Ω switch connection between two ports

s Undershoot Hardened to -2.0V.

s Minimal propagation delay through the switch

s Zero ground bounce in flow-through mode

s Control inputs compatible with TTL level

s See Applications Note AN-5008 for details.

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

UHC

 is a trademark of Fairchild Semiconductor Corporation.

Order Number

Package Number

Package Description

FSTU3384WM

M24B

24-Lead Small Outline Integrated Circuit (SOIC), JEDEC MO-153 4.4mm Wide

FSTU3384QSC

MQA24

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

FSTU3384MTC

MTC24

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

Pin Names

Description

OEA, OEB

Bus Switch Enable

Bus A

Bus B

OEAOEB

Function

LL

Connect

LH

HIGH-Z State

Connect

H

L

HIGH-Z State

Connect

H

H

HIGH-Z State

HIGH-Z State

Disconnect