## Overview of the FST16213 The **FST16213** is a high-speed CMOS bus exchange switch. It is primarily used in digital systems to provide a high-speed connection between two buses or to swap signals between them. It is part of the "Bus Switch" family, known for having near-zero propagation delay. --- ### 1. Key Technical Specifications | Parameter | Description | | :--- | :--- | | **Logic Family** | FST (Bus Switch) | | **Configuration** | 24-Bit Bus Exchange Switch | | **Supply Voltage (Vcc)** | 4.0V to 5.5V | | **Propagation Delay** | < 0.25 ns (Near Zero) | | **On-Resistance (Ron)** | 4Ω to 7Ω (Typical) | | **Input/Output Capacitance** | Low (Typically < 10pF) | | **Package Types** | TSSOP, SSOP | --- ### 2. Functional Description The FST16213 consists of 24 sets of switches. It is designed to allow two different 12-bit buses to be connected or cross-exchanged. This is particularly useful in memory interleaving or data path multiplexing. #### Operating Modes The device is controlled by Select (**S0, S1, S2**) pins. Depending on the logic levels applied to these pins, the switch performs different routing functions: 1. **Isolation:** No connection between ports. 2. **A to B Connection:** Port A is directly connected to Port B. 3. **Exchange:** Port A signals are routed to a different set of B pins (swapping). --- ### 3. Electronic Characteristics * **Zero Propagation Delay:** Because the device acts like a physical wire (a low-resistance NMOS switch), it does not add the gate delays associated with standard logic buffers. * **Bidirectional Flow:** Data can flow from A to B or B to A without needing a direction control pin. * **Hot Plug Protection:** Many variants support "Power-off High Impedance," meaning the device won't interfere with the bus when the power supply is off. --- ### 4. Common Applications * **Memory Interleaving:** Swapping data bytes between memory banks. * **Bus Swapping:** Reconfiguring data paths in CPU-to-Peripheral communication. * **Signal Level Shifting:** Can be used for 5V to 3.3V translation if Vcc is biased appropriately. * **Voltage Isolation:** Disconnecting segments of a bus to reduce capacitive loading. --- ### 5. Pin Configuration Example (Simplified) ```text +-------+ S0 --| |-- A1 S1 --| FST |-- B1 S2 --| 16213 |-- A2 VCC --| |-- B2 GND --| |-- ... +-------+ ```