© 2005 Fairchild Semiconductor Corporation

DS500021

www.fairchildsemi.com

June 1997

Revised January 2005

FST3244

8-Bit Bus Switch

General Description

The Fairchild Switch FST3244 provides 8-bits of high-

speed CMOS TTL-compatible bus switching in a standard

’244 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 two 4-bit switches with separate

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

■ 4

: 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:

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

Note 1: “_NL” indicates Pb-Free package (per JEDEC J-STD-020B). Device available in Tape and Reel only.

Logic Diagram

Pin Descriptions

Connection Diagram

Truth Table

Order Number

Package Number

Package Description

FST3244WM

M20B

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

FST3244QSC

MQA20

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

FST3244MTC

MTC20

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

FST3244MTCX_NL

(Note 1)

MTC20

Pb-Free 20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153,

4.4mm Wide

Pin Name

Description

Bus Switch Enable

1A, 2A

Bus A

1B, 2B

Bus B

Inputs

Inputs/Outputs

1A, 1B

2A, 2B

LL

1A

1B

2A

2B

LH

1A

1B

Z

HL

Z

2A

2B

HH

Z

Z