Integrated Device Technology, Inc.

COMMERCIAL TEMPERATURE RANGES

AUGUST 1996

©1996 Integrated Device Technology, Inc.

10.3

DSC-3257/3

QUAD 2:1 MUX/DEMUX

BUS SWITCH

IDT74FST3257

PRELIMINARY

1

PIN DESCRIPTION

capability. Thus they generate little or no noise of their own

while providing a low resistance path for an external driver.

These devices connect input and output ports through an n-

channel FET. When the gate-to-source junction of this FET is

adequately forward-biased the device conducts or the resis-

tance between input and output ports is small.

Without

adequate bias on the gate-to-source junction of the FET, the

has hot insertion capability.

The low on-resistance and simplicity of the connection

between input and output ports reduces the delay in this path

to close to zero.

The FST3257 provides a 4-bit 2:1 multiplexer/demultiplexer.

The S pin controls the mux select and the

E pin serves as the

switch enable.

3257 tbl 01

FEATURES:

• Bus switches provide zero delay paths

• Extended commercial range of –40

°C to +85°C

• Low switch on-resistance:

FST3xxx – 5

Ω

• TTL-compatible input and output levels

• ESD > 2000V per MIL-STD-883, Method 3015;

> 200V using machine model (C = 200pF, R = 0)

• Available in QSOP and SOIC

Pin Names

I/O

Description

I/O

Port 0

I/O

Port 1

E

I

Switch Enable (Active Low)

S

I

Mux Select

I/O

Port Z

The IDT logo is a registered trademark of Integrated Device Technology, Inc.

3257 drw 01

3257 drw 02

SOIC/QSOP

TOP VIEW

5

6

7

8

1

2

3

4

14

13

12

11

10

9

S

GND

Vcc

SO16-1

SO16-7

15

16

E

3 Channels

S

E

FUNCTIONAL BLOCK DIAGRAM

PIN CONFIGURATION

DESCRIPTION:

The FST3257 belongs to IDT's family of Bus switches. Bus

switch devices perform the function of connecting or isolating

two ports without providing any inherent current sink or source