## Technical Overview of the FST3383WM The **FST3383WM** is a high-performance CMOS 10-bit Bus Exchange Switch produced by Fairchild Semiconductor (now part of ON Semiconductor). It is primarily designed for high-speed bus switching and data routing. ### 1. Key Functionality The device consists of ten high-speed CMOS TTL-compatible bus switches. It features a unique **"Bus Exchange"** architecture, allowing it to act as a 10-bit cross-point switch. This means it can route signals between two sets of I/O ports (A and B) or exchange the paths. --- ### 2. Technical Specifications | Parameter | Specification | | :--- | :--- | | **Logic Type** | Bus Exchange Switch | | **Configuration** | 10-Bit (5-bit x 2) | | **Supply Voltage (Vcc)** | 4.0V to 5.5V | | **On-Resistance (Ron)** | 4Ω (Typical) | | **Propagation Delay** | 0.25 ns (Max) | | **Package Type** | SOIC-24 (Wide Body) | | **Operating Temp** | -40°C to +85°C | --- ### 3. Pinout and Control Logic The FST3383WM operates based on two control pins: **Output Enable ($\overline{OE}$)** and **Select (S)**. These pins determine how the A-ports ($A_1-A_{10}$) connect to the B-ports ($B_1-B_{10}$). #### Truth Table | $\overline{OE}$ | S | Function | Description | | :---: | :---: | :--- | :--- | | L | L | Connect | $A_n$ connected to $B_n$ | | L | H | Exchange | $A_1 \leftrightarrow B_2$, $A_2 \leftrightarrow B_1$, etc. | | H | X | Disconnect | High Impedance (Hi-Z) State | --- ### 4. Core Features & Benefits * **Low On-Resistance:** The 4Ω typical resistance ensures minimal voltage drop and low power dissipation across the switch. * **Zero Propagation Delay:** Because it is a simple FET switch rather than a buffer, it introduces negligible timing skew (under 250 picoseconds). * **Bidirectional Flow:** Data can flow in either direction without needing a direction control pin. * **Under-shoot Protection:** It includes circuitry to prevent signal undershoot, protecting sensitive downstream components. ### 5. Common Applications 1. **Memory Interleaving:** Swapping data lines between different memory banks. 2. **Bus Swapping:** Reconfiguring data paths between CPUs and peripherals. 3. **Hot-Plug Protection:** Isolating buses during live insertion of modules. 4. **Signal Multiplexing:** Selecting between multiple data sources for a single bus. ---