## Overview of the FST3384 IC The **FST3384** is a high-performance **10-bit Bus Switch** designed with CMOS technology. It is primarily used for high-speed switching and level shifting in computing and networking environments. --- ### 1. Pin Configuration and Internal Logic The device consists of ten independent high-speed CMOS FET switches. It is typically organized as two banks of five switches. | Pin Type | Description | | :--- | :--- | | **A0 - A9** | Data Inputs / Outputs (Port A) | | **B0 - B9** | Data Inputs / Outputs (Port B) | | **$\overline{OE}_1, \overline{OE}_2$** | Output Enable (Active LOW) | | **Vcc** | Power Supply (Typically 5V) | | **GND** | Ground | --- ### 2. Key Specifications The electronic characteristics of the FST3384 make it ideal for low-latency applications. * **Propagation Delay:** Practically zero (< 0.25ns). The device acts as a low-resistance wire when closed. * **On-Resistance ($R_{on}$):** Typically **$5\Omega$**, ensuring minimal voltage drop across the switch. * **Voltage Range:** Operates at a standard **5V Vcc**. * **Off-State Leakage:** Very low, preventing power drain on inactive buses. --- ### 3. Operating Truth Table The FST3384 is controlled by the Output Enable ($\overline{OE}$) pins. When $\overline{OE}$ is LOW, the switch is closed (ON). When HIGH, the switch is open (High-Impedance). | $\overline{OE}_1$ | $\overline{OE}_2$ | A0-A4 Status | A5-A9 Status | | :---: | :---: | :--- | :--- | | L | L | Connected to B0-B4 | Connected to B5-B9 | | L | H | Connected to B0-B4 | **High-Z** (Disconnected) | | H | L | **High-Z** (Disconnected) | Connected to B5-B9 | | H | H | **High-Z** (Disconnected) | **High-Z** (Disconnected) | --- ### 4. Primary Applications The FST3384 is frequently used in the following electronic circuits: 1. **5V to 3.3V Level Shifting:** By placing a diode in series with Vcc or using specific biasing, the FST3384 can protect 3.3V components from 5V signals. 2. **Bus Isolation:** Used to "hot-swap" components by isolating a daughterboard from a main system bus. 3. **Signal Multiplexing:** Allowing multiple data sources to share a single bus path without signal interference. --- ### 5. Simple Implementation Example In a digital circuit, the FST3384 is wired directly between two buses. ```c // Conceptual Logic for controlling FST3384 via an MCU void selectBus(bool enable) { if (enable) { digitalWrite(OE_PIN, LOW); // Switches are ON, data flows A <-> B } else { digitalWrite(OE_PIN, HIGH); // Switches are OFF, Hi-Z state } } ```