FST3253MX

Overview

The FST3253MX is a dual 4:1 high-speed CMOS TTL-compatible multiplexer/demultiplexer bus switch manufactured by onsemi. It operates within a supply voltage range of 4.0V to 5.5V and supports an input/output voltage range of 0V to 5.5V. The device features a typical switch on resistance of 4Ω at 4.5V, with a maximum propagation delay of 6.3ns from select inputs to the bus. It includes two independent bus switches controlled by OE1/OE2 enable pins and S0/S1 select inputs, housed in a 16-lead Small Outline Integrated Circuit (SOIC) package.

Feature Summary

• Dual 4:1 multiplexer/demultiplexer architecture providing independent switching control for two ports
• Low on-resistance switch connection enabling signal transfer without adding significant propagation delay or ground bounce noise
• TTL-compatible control inputs allowing direct interfacing with standard logic families
• High-impedance state isolation when output enables are deactivated

Applications

• Bus switching applications requiring low insertion loss
• Multiplexing data lines in digital systems
• Demultiplexing signals to multiple destinations
• Interface bridging between different logic domains

Procurement Notes

Verify the specific ordering code suffix against current manufacturer databases, as part numbers may have transitioned from Fairchild Semiconductor nomenclature to ON Semiconductor standards following integration. Confirm package availability and ensure compliance with RoHS directives by checking the Material Composition Declaration. Validate that the selected variant matches the required operating temperature range and pin configuration for your design.

Selection Notes

Select this component for applications requiring minimal propagation delay and low power consumption in a compact surface-mount package. Ensure the design accommodates the recommended operating conditions, specifically the 4.0V to 5.5V supply voltage range. Consider the 16-lead SOIC footprint for PCB layout and verify that unused control inputs are tied to defined logic levels to prevent floating states during operation.

Part Context

The FST3253 belongs to the FST3xxx series of high-speed CMOS bus switches originally developed by Fairchild Semiconductor. This family utilizes proven switch technology designed to provide low on-resistance and minimal signal distortion. The device integrates dual independent switches into a single package, offering a space-efficient solution for managing multiple data paths in complex digital circuits.

Replacement Considerations

Check the official ON Semiconductor website for updated part numbers resulting from the Fairchild integration, as underscores may have been replaced with dashes. Verify functional compatibility if substituting with other devices from the FST3xxx series or similar bus switch families.