© 2001 Fairchild Semiconductor Corporation

DS500448

www.fairchildsemi.com

June 2001

Revised June 2001

FSTD3125

4-Bit Bus Switch with Level Shifting

General Description

The Fairchild Switch FSTD3125 provides four high-speed

CMOS TTL-compatible bus switches. The low On Resis-

tance of the switch allows inputs to be connected to out-

puts without adding propagation delay or generating

integrated into the circuit to allow for level shifting between

5V inputs and 3.3V outputs.

The device is organized as four 1-bit switches with sepa-

rate OE inputs. 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 Minimal propagation delay through the switch

s Zero bounce in flow-through mode

s Control inputs compatible with TTL level

s TruTranslation

 voltage translation from 5.0V inputs to

3.3V outputs

Ordering Code:

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

Connection Diagrams

Pin Assignment for SOIC and TSSOP

Pin Assignment for QSOP

Pin Descriptions

Truth Table

TruTranslation

 is a trademark of Fairchild Semiconductor Corporation.

Order Number

Package Number

Package Description

FSTD3125M

M14A

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

FSTD3125QSC

MQA16

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

FSTD3125MTC

MTC14

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

Pin Name

Description

Bus Switch Enables

1A, 2A, 3A, 4A

Bus A

1B, 2B, 3B, 4B

Bus B

NC

Not Connected

Inputs

Inputs/Outputs

OE

A, B

LA

= B

HZ