74FST3257DR2

The 74FST3257DR2 is a logic signal switch with multiplexers, decoders and drivers designed by Fairchild Semiconductor. This device is capable of operating under 3.3V to 5.5V with high speed performance of 190MHztypical for -3dB bandwidth. This device has two bi-directional blocks (Group A and Group B) where each group contains four differential pairs (pins \A1/A2, \B1/B2, \C1/C2, and \D1/D2).

• Application Field

The 74FST3257DR2 is extensively used in digital audio-visual devices such as DVD and Blu-Ray players, digital TVs, and IPTVs for improving picture quality with its noise-free digital switching functions. It also finds applications in communication networks and automotive infotainment systems.

• Working Principle

The 74FST3257DR2 operates with two modes, the auto mode and the manual mode. In auto mode, each group of four differential pairs is configured in an active low configuration. This configuration allows the device to automatically make switching decisions based on the logic levels presented at the pins. In manual mode, the user can manually make switching decisions regarding each differential pair.The 74FST3257DR2 also provides a slew rate control function that allows the user to set a throttle control on the output of the device. This feature helps to eliminate unwanted output glitches and improve the signal integrity in the output.The device also features a Soft-Switch mode that helps to reduce ground bounce associated with switching operations. This helps reduce EMI and RF noise associated with switching functions.The device is equipped with an internal level clamping circuit that helps to prevent false switching due to noise. This internal clamping circuit also reduces the possibility of power supply current droop due to surges in the power rail.Finally, the device is equipped with an On-Circuit Thermal Protection system that helps to prevents damage due to overtemperatures. This thermal protection system has a built-in hot-swap protection feature that helps to protect both the device and the surrounding circuitry from catastrophic damage due to thermal events.