FSTU3125QSC

Overview

The FSTU3125QSC is a high-speed CMOS TTL-compatible bus switch manufactured by Fairchild Semiconductor. It provides four independent one-bit switches with separate active-low output enable (/OE) inputs, packaged in a 16-pin SSOP. The device features an integrated undershoot hardened circuit (UHC) that protects the A and B ports against voltage undershoot down to −2V below ground. When /OE is LOW, Port A connects to Port B; when HIGH, the switch opens to a high-impedance state.

Feature Summary

• Undershoot hardened to -2V on all I/O ports
• Low on-resistance for minimal propagation delay
• Zero bounce operation in flow-through mode

Applications

• High-speed data processing logic replacement
• Bus isolation for mass storage systems
• Clock gating applications

Procurement Notes

Verify the specific suffix QSC corresponds to the 16-pin SSOP package configuration. Confirm the component meets RoHS standards as indicated in the manufacturer documentation. Ensure the operating temperature range of -40°C to +85°C aligns with system requirements before finalizing procurement.

Selection Notes

Select this component when undershoot protection is required for signals extending below ground potential. It serves as a direct functional alternative to standard bus switches lacking UHC technology. Verify pin compatibility with existing designs if replacing similar devices from the FST3125 family.

Part Context

This part belongs to the FSTU series, which extends the standard FST3125 functionality by adding robust undershoot protection. While the base FST3125 lacks this feature, the FSTU variant ensures reliable operation in environments prone to signal ringing or ground bounce issues.

Replacement Considerations

The FST3125QSC is a compatible substitute but lacks the -2V undershoot protection found in the FSTU3125QSC.