FSTU3257_06 Datasheet, PDF (1/6 Pages) Fairchild Semiconductor – Quad 2:1 Multiplexer/Demultiplexer Bus Switch with 2V Undershoot Protection

August 1999
Revised October 2006
FSTU3257
Quad 2:1 Multiplexer/Demultiplexer Bus Switch with
2V Undershoot Protection
General Description
The Fairchild Switch FSTU3257 is a quad 2:1 high-speed
CMOS TTL-compatible multiplexer/demultiplexer bus
switch. The low on resistance of the switch allows inputs to
be connected to outputs without adding propagation delay
or generating additional ground bounce noise.
When OE is LOW, the select pin connects the A Port to the
selected B Port output. The A and B Ports are “undershoot
hardened” with Undershoot Hardened Circuit (UHC®¥) pro-
tection to support an extended range of 2.0V below
ground. Fairchild’s integrated UHC senses undershoot at
the I/O and responds by preventing voltage differentials
from developing and turning on the switch. When OE is
HIGH, the switch is OPEN and a high-impedance state
exists between the two ports.
Features
s Undershoot hardened to 2V (A and B Ports)
s Soft enable turn-on to minimize bus to bus charge
sharing during enable
s 4: switch connection between two ports.
s Minimal propagation delay through the switch.
s Low l_CC.
s Zero bounce in flow-through mode.
s Control inputs compatible with TTL level.
s See Applications Note AN-5008 for details
Ordering Code:
Order Number Package Number
Package Description
FSTU3257M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow
FSTU3257QSC
MQA16
16-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150" Wide
FSTU3257MTC
MTC16
16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.
Logic Diagram
Connection Diagram
Pin Descriptions
Pin Name
OE
S
A
B₁–B₂
Description
Bus Switch Enable
Select Input
Bus A
Bus B
Truth Table
S
OE
X
H
L
L
H
L
UHC®¥ is a registered trademark of Fairchild Semiconductor Corporation.
© 2005 Fairchild Semiconductor Corporation DS500302
Function
Disconnect
A B₁
A B₂
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