### Overview of the FSUSB45 The **FSUSB45** is a high-performance, low-power USB 2.0 switch designed specifically for switching high-speed (480 Mbps) USB signals. It is commonly used in mobile devices and consumer electronics where a single USB port needs to be shared between two different internal controllers or chips. --- ### Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Switch Type** | 2:1 (DPDT) High-Speed USB Switch | | **Bandwidth** | > 720 MHz | | **Operating Voltage (Vcc)** | 3.0V to 4.4V | | **On-Resistance (Ron)** | 6.5 $\Omega$ (Typical) | | **Off-Isolation** | -30 dB at 240 MHz | | **ESD Protection** | Up to 8kV (HBM) | | **Package Options** | MicroPak™-10, DQFN-10 | --- ### Internal Functional Components 1. **Select Pin (S):** This is a CMOS control input. A logic `Low` or `High` determines which USB path is active (D+/D- to Port 1 or Port 2). 2. **Enable Pin (/OE):** The Output Enable pin (usually active-low) allows the chip to enter a high-impedance state, effectively disconnecting all paths and minimizing power consumption. 3. **High-Speed Switches:** Precision analog switches optimized for low capacitance (approx. 7pF) to ensure that the USB 2.0 eye diagram remains compliant even at high frequencies. --- ### Pin Configuration (Common 10-Pin Layout) | Pin Name | Function | | :--- | :--- | | **Vcc / GND** | Power supply and Ground. | | **S** | Select logic input. | | **D+, D-** | Common USB data pins (connected to the connector). | | **1D+, 1D-** | Path 1 data lines (e.g., to Application Processor). | | **2D+, 2D-** | Path 2 data lines (e.g., to Modem or Debugger). | | **/OE** | Output Enable (Power-down control). | --- ### Typical Application Circuit The FSUSB45 is placed between a USB Type-C or Micro-B connector and two internal ICs. ```mermaid graph LR USB_Connector --- FSUSB45 FSUSB45 -- Select High --> SoC_USB_Host FSUSB45 -- Select Low --> Modem_or_Charger_IC ``` --- ### Key Advantages * **Minimal Signal Distortion:** High bandwidth ensures that the 480 Mbps data edges are not rounded off. * **Low Power Consumption:** Designed for battery-operated devices, drawing very little current during operation. * **Space Efficient:** The MicroPak packaging is extremely small, making it ideal for smartphones and tablets.