The **FST3383QSC** is a high-speed CMOS 10-bit bus switch/exchange switch manufactured by Fairchild Semiconductor (now part of onsemi). It is designed to facilitate high-speed data switching with minimal propagation delay. --- ## 1. Technical Specifications The following table summarizes the key electrical and physical characteristics of the FST3383QSC. | Parameter | Specification | | :--- | :--- | | **Logic Family** | FST (Bus Switch) | | **Number of Bits** | 10-Bit (5-bit exchange) | | **Supply Voltage ($V_{CC}$)** | 4.0V to 5.5V | | **On-Resistance ($R_{ON}$)** | 4Ω (Typical) at 5V | | **Propagation Delay** | 0.25 ns (Max) | | **Operating Temperature** | -40°C to +85°C | | **Package Type** | QSOP-24 (Quarter Size Outline Package) | --- ## 2. Pin Configuration and Functions The device operates as a 10-bit bus switch or a 5-bit bus exchange. The control pins determine how the A and B ports are connected. ### Key Control Logic | Control Pin ($\overline{BE}$) | Bus Exchange ($BX$) | Connection State | | :--- | :--- | :--- | | High (1) | X (Don't Care) | Disconnected (Hi-Z) | | Low (0) | Low (0) | Direct: $A_n$ to $B_n$ | | Low (0) | High (1) | Exchange: $A_n$ to $B_{n+1}$ | --- ## 3. Key Features * **Low On-Resistance:** The 4Ω resistance ensures that the switch does not significantly degrade the signal integrity or timing. * **Zero Propagation Delay:** Because it acts as a simple wire connection when enabled, it introduces virtually no delay compared to standard logic gates. * **Hot Insertion Capable:** The device supports "hot-swapping," meaning it can be connected/disconnected while the system is powered. * **TTL Compatible Inputs:** Control inputs are compatible with standard TTL voltage levels. --- ## 4. Common Applications The FST3383QSC is typically used in environments where high-speed data routing is required without adding logic complexity: 1. **Memory Interleaving:** Switching between different banks of SDRAM. 2. **Bus Swapping:** Exchanging data bytes in 16-bit or 32-bit systems. 3. **Signal Isolation:** Disconnecting a subsystem from the main bus to reduce capacitive loading. 4. **Voltage Level Translation:** If $V_{CC}$ is limited, it can be used for basic 5V to 3.3V level shifting. ---