FSTD3125QSC

Overview

The FSTD3125QSC is a high-speed CMOS digital bus switch manufactured by Fairchild Semiconductor. It provides four independent one-bit switches with separate active-low output enable inputs (/OE). The device facilitates signal routing between two ports (Port A and Port B) while supporting voltage translation, specifically enabling level shifting from 5V to 3.3V domains. It features low on-resistance to minimize propagation delay and ground bounce noise. The component operates within an industrial temperature range of -40°C to +85°C and is housed in a 16-pin SSOP package.

Feature Summary

• Supports voltage translation between 5V and 3.3V logic levels
• Provides four independent high-speed bus switches with individual control
• Features low on-resistance for minimal signal degradation
• Compatible with TTL logic input levels

Applications

• Voltage translation between 5V and 3.3V systems
• Hot-swapping applications requiring signal isolation
• Bus isolation in data processing circuits
• Clock gating and capacitance reduction

Procurement Notes

Verify the specific suffix QSC against the manufacturer's official documentation to confirm the exact package type and tape-and-reel configuration. Ensure the ordering information matches the required lead-free JEDEC standards and operating temperature range specified in the datasheet before finalizing procurement.

Selection Notes

Select this component when bidirectional level shifting between 5V and 3.3V is required alongside standard bus switching functionality. It serves as a suitable replacement for basic bus drivers where voltage domain crossing is necessary. Verify that the 16-pin SSOP package fits the target PCB layout constraints.

Part Context

This part belongs to the FST series of high-speed CMOS bus switches developed by Fairchild Semiconductor. The family utilizes proven QuickSwitch technology designed to provide low resistance and minimal propagation delay. The FSTD3125 variant specifically adds level-shifting capabilities compared to the standard FST3125 model.

Replacement Considerations

The FST3125QSC is a pin-compatible alternative if level shifting is not required. For identical functionality including level shifting, verify the FSTD3125M or FSTD3125MX variants from Fairchild/ON Semiconductor.