Fairchild FST3126 4-Bit Bus Switch Data Handbook
Summary
The FST3126 is a high-speed 4-bit CMOS/TTL bus switch designed for reliable signal interconnection between two digital ports (A and B). It features low on resistance, minimal propagation delay, and flow-through mode compatibility. This manual provides comprehensive technical details, including electrical characteristics, absolute maximum ratings, pin assignments for multiple packages (SOIC, QSOP, TSSOP), and connection diagrams. It is an essential resource for electronic engineers and circuit designers who require precise, high-performance signal switching components in their digital systems.
Page 1 Text Content
3126 4-B it B s S itch
August 1997 Revised January 2005
FST3126 4-Bit Bus Switch General Description Features The Fairchild Switch FST3126 provides four high-speed ■4Ω switch connection between two ports. CMOS TTL-compatible bus switches. The low on resis-
■Minimal propagation delay through the switch.
tance of the switch allows inputs to be connected to out-
■Low l CC.
puts without adding propagation delay or generating
additional ground bounce noise. ■Zero bounce in flow-through mode. The device is organized as four 1-bit switches with sepa- ■Control inputs compatible with TTL level.
rate OE inputs. When OE is HIGH, the switch is ON and Port A is connected to Port B. When OE is LOW, the switch is OPEN and a high-impedance state exists between the two ports.
Ordering Code: Order Number Package Number Package Description FST3126M M14A 14-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow FST3126QSC MQA16 16-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150" Wide FST3126MTC MTC14 14-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Logic Diagram Connection Diagrams
Pin Assignment for SOIC and TSSOP
Pin Assignment for QSOP
Pin Descriptions
Pin Name Description
Truth Table
OE1, OE2, OE3, OE4 Bus Switch Enables 1A, 2A, 3A, 4A Bus A Inputs Inputs/Outputs 1B, 2B, 3B, 4B Bus B OE A,B
NC Not Connected
© 2005 Fairchild Semiconductor Corporation DS500044 www.fairchildsemi.com
Page Summary Contents For Fairchild FST3126 4-Bit Bus Switch Data Handbook
Manual Details
| Brand | Fairchild |
|---|---|
| Pages | 5 |
| File Size | 116.55 KB |
| Published | July 10, 2026 |
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Frequently Asked Questions
What is the primary function of the FST3126 device?
It provides four high-speed, CMOS TTL-compatible switches for connecting or disconnecting signals between two ports (Bus A and Bus B).
How does the switch operate based on the OE input?
When OE is HIGH, the switch turns ON, connecting Port A to Port B. When OE is LOW, the switch opens, creating a high-impedance state.
What power supply voltage range can be recommended for operation?
The recommended operating condition for the Power Supply (VCC) is 4.0V to 5.5V DC.
Are there different physical packages available for ordering?
Yes, it is available in SOIC (14-Lead), QSOP (16-Lead), and TSSOP (14-Lead) packages.