## FSUSB46L8X: High-Speed USB 2.0 Switch The **FSUSB46L8X** is a high-performance, low-power analog switch specifically designed for switching high-speed (480Mbps) USB 2.0 signals. It is commonly used in mobile devices to allow a single USB port to be shared between multiple internal components. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Function** | Dual 2:1 High-Speed USB 2.0 Switch | | **Supply Voltage ($V_{CC}$)** | 2.4V to 4.4V | | **Data Rate** | Up to 480 Mbps | | **On Resistance ($R_{ON}$)** | 3.9 $\Omega$ (Typical) | | **Bandwidth (-3dB)** | 720 MHz | | **Operating Temperature** | -40°C to +85°C | | **Package** | 8-Lead MicroPak (1.6mm x 1.6mm) | --- ### 2. Functional Description The device acts as a **Double-Pole, Double-Throw (DPDT)** switch. It consists of two sets of high-speed switches that route the USB $D+$ and $D-$ signals from a common port to one of two different destinations. #### Main Features: * **Low Capacitance:** Designed to maintain signal integrity for USB 2.0 high-speed eye diagrams. * **Power-Off Protection:** When $V_{CC} = 0V$, the $D+/D-$ pins remain in a high-impedance state, preventing current leakage back into the system. * **Over-Voltage Tolerance:** The I/O pins can handle up to 5.25V even if the supply voltage is lower. --- ### 3. Pin Configuration & Logic The FSUSB46 typically uses a simple control logic (S) to determine the path of the signal. | SEL (Control) | Function | | :--- | :--- | | **Low (L)** | $D+/D-$ connected to Port 1 | | **High (H)** | $D+/D-$ connected to Port 2 | --- ### 4. Typical Application Circuit The FSUSB46L8X is frequently used in smartphones to switch the Micro-USB or USB-C connector between the **Application Processor** and a **Baseband Modem** or an **Audio Codec**. ```mermaid graph LR USB_Port(USB Connector) --- FSUSB46{FSUSB46L8X} FSUSB46 --- Path1(Main Processor) FSUSB46 --- Path2(Secondary Module/Modem) Control(GPIO Control) --> FSUSB46 ``` --- ### 5. Why use the FSUSB46L8X? 1. **Space Efficiency:** The MicroPak-8 package is extremely small, ideal for dense PCB layouts. 2. **Signal Integrity:** High bandwidth (720 MHz) ensures that the high-speed USB pulse edges are not rounded, preventing data errors. 3. **Battery Conservation:** Low quiescent current ensures minimal drain on portable device batteries.