Fairchild FSTU3257 Data Sheet, User Manual
Summary
The FSTU3257 is a quad 2:1 high-speed CMOS multiplexer/demultiplexer bus switch from Fairchild. It features undershoot hardened protection to -2V on both ports using UHC technology, minimal propagation delay, and zero bounce in flow-through mode. Available in 16-lead SOIC, QSOP, and TSSOP packages with TTL-compatible control inputs, the low on-resistance enables input-to-output connection without added delay or ground bounce. It targets digital hardware designers working on bus switching and signal multiplexing in computing and telecommunications.
Page 1 Text Content
3257 Q ad 2:1 M ltip lexer/D em ltip lexer B s S itch ith 2V ersh t P ro tectio
August 1999 Revised October 2006
FSTU3257 Quad 2:1 Multiplexer/Demultiplexer Bus Switch with 2V Undershoot Protection General Description Features The Fairchild Switch FSTU3257 is a quad 2:1 high-speed ■Undershoot hardened to 2V (A and B Ports) CMOS TTL-compatible multiplexer/demultiplexer bus ■Soft enable turn-on to minimize bus to bus charge switch. The low on resistance of the switch allows inputs to
sharing during enable
be connected to outputs without adding propagation delay
■4: switch connection between two ports.
or generating additional ground bounce noise.
■Minimal propagation delay through the switch.
When OE is LOW, the select pin connects the A Port to the
■Low l CC.
selected B Port output. The A and B Ports are “undershoot hardened” with Undershoot Hardened Circuit (UHC®¥) pro- ■Zero bounce in flow-through mode. tection to support an extended range of 2.0V below
■Control inputs compatible with TTL level.
ground. Fairchild’s integrated UHC senses undershoot at
■See Applications Note AN-5008 for details
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.
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
Truth Table
Pin Descriptions
Pin Name Description OE Function
Disconnect
OE Bus Switch Enable
Select Input
Bus A
B1–B2 Bus B
UHC®¥ is a registered trademark of Fairchild Semiconductor Corporation.
© 2005 Fairchild Semiconductor Corporation DS500302 www.fairchildsemi.com
Page Summary Contents For Fairchild FSTU3257 Data Sheet, User Manual
Manual Details
| Brand | Fairchild |
|---|---|
| Pages | 6 |
| File Size | 200.46 KB |
| Published | June 17, 2026 |
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Frequently Asked Questions
What is the max undershoot protection for the A and B ports?
The A and B ports are undershoot hardened to support an extended range of 2.0V below ground.
When OE is HIGH, what state is the switch in?
When OE is HIGH, the switch is OPEN and a high-impedance state exists between the two ports.
What is the recommended supply voltage range for operation?
The recommended operating supply voltage (VCC) range is 4.0V to 5.5V.
What packages is the FSTU3257 available in?
It is available in 16-lead SOIC, QSOP, and TSSOP packages, also in Tape and Reel with suffix X.