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Fairchild FST3245 8-Bit Bus Switch Data Manual

Summary

This high-speed, TTL-compatible 8-bit bus switch provides reliable connection between two digital ports with minimal propagation delay and zero bounce in flow-through mode. Ideal for engineers designing robust electronic systems, the manual offers critical specifications covering operational pin configurations, DC electrical characteristics, absolute maximum ratings, and recommended operating conditions. It ensures optimal integration of this versatile component into your circuit design plans.

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FST3245 — 8-B it B us Sw itch

March 2008

FST3245 — 8-Bit Bus Switch Features Description

4Ω Switch Connection between Two Ports The FST3245 switch provides eight-bits of high-speed CMOS TTL-compatible bus switching in a standard ’245

Minimal Propagation Delay through the Switch

pin-out. The low on resistance allows inputs to be connected to outputs without adding propagation delay

Low ICC

or generating additional ground bounce noise.

Zero Bounce in Flow-through Mode

The device is organized as an eight-bit switch. When

Control Inputs Compatible with TTL Level

/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.

Ordering Information

Operating

Part Number Temperature Package Packing

Method

Range

FST3245WMX -40 to +85°C 20-Lead, Small Outline Integrated Circuit (SOIC), JEDEC

MS-013, 0.300-inch Wide Tape and Reel

FST3245QSC -40 to +85°C 20-Lead Quarter Size Outline Package (QSOP), JEDEC

MO-137, 0.150-inch Wide Tube

FST3245QSCX -40 to +85°C 20-Lead Quarter Size Outline Package (QSOP),

JEDEC MO-137, 0.150-inch Wide Tape and Reel

FST3245MTC -40 to +85°C 20-Lead Thin Shrink Small Outline Package (TSSOP),

JEDEC MO-153, 4.4mm Wide Tube

FST3245MTCX -40 to +85°C 20-Lead Thin Shrink Small Outline Package (TSSOP),

JEDEC MO-153, 4.4mm Wide Tape and Reel

All packages are lead free per JEDEC: J-STD-020B standard. The Fairchild switch family derives from and embodies Fairchild’s proven switch technology used for several years in its 74LVX3L384 (FST3384) bus switch product.

Logic Diagram

Figure 1. Logic Diagram

©1997 Fairchild Semiconductor Corporation www.fairchildsemi.com FST3245 • Rev. 1.0.2

Page Summary Contents For Fairchild FST3245 8-Bit Bus Switch Data Manual

Page 1 FST3245 — 8-B it B us Sw itch March 2008 FST3245 — 8-Bit Bus Switch Features Description 4Ω Switch Connection between Two Ports The FST3245 switch provides eight-bits of high-speed CMOS TTL-compatible...
Page 2 FST3245 — 8-B it B us Sw itch Pin Configuration NC VCC A0 /OE GND B7 Figure 2. Pin Configuration Pin Descriptions Pin # Pin Names Description 1 NC No Connnect 19 /OE Bus Switch Enable 2,3,4,5,6,7,8,9 ...
Page 3 FST3245 — 8-B it B us Sw itch Absolute Maximum Ratings Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating...
Page 4 FST3245 — 8-B it B us Sw itch DC Electrical Characteristics Typical values are at VCC = 5.0V and TA = 25°C. TA=-40 to +85°C Symbol Parameter Conditions VCC (V) Units Min. Typ. Max. VIK Clamp Diode Vol...
Page 5 FST3245 — 8-B it B us Sw itch AC Loadings and Waveforms Notes: Input driven by 50Ω source terminated in 50Ω. CL includes load and stray capacitance. Input PRR = 1.0MHz, tw = 500ns. Figure 3. AC Test C...
Page 6 FST3245 — 8-B it B us Sw itch Physical Dimensions PIN ONE 1.27 INDICATOR 0.25 BC AM LAND PATTERN RECOMMENDATION 2.65 MAX SEE DETAIL A 0.30 0.10 SEATING PLANE NOTES: UNLESS OTHERWISE SPECIFIED A) THIS ...
Page 7 FST3245 — 8-B it B us Sw itch Physical Dimensions LAND PATTERN TOP VIEW RECOMMENDATION END VIEW SIDE VIEW DETAIL A Figure 6. 20-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150-inch Wide ...
Page 8 FST3245 — 8-B it B us Sw itch Physical Dimensions Figure 7. 20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide Package drawings are provided as a service to customers consider...
Page 9 FST3245 — 8-B it B us Sw itch © 1997 Fairchild Semiconductor Corporation www.fairchildsemi.com FST3245 • Rev. 1.0.2 9

Manual Details

Brand Fairchild
Pages 9
File Size 434.50 KB
Published July 15, 2026
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Frequently Asked Questions

How is the FST3245 switch activated?

The device connects Bus A to Bus B when /OE is LOW, turning it ON; connecting it HIGH keeps the switch open.

What determines if the switch output causes signal delay?

Its low on resistance (R_ON) allows inputs to be connected to outputs without adding propagation delay.

What is the typical operating voltage range for the FST3245?

The recommended Power Supply Operating range is between 4.0 V and 5.5 V.

Which packages are available for ordering this switch?

Available packages include QSOP (e.g., FST3245QSC) and TSSOP (e.g., FST3245MTC).