## FSUSB40: High-Speed USB 2.0 (480 Mbps) Switch The **FSUSB40** is a high-performance, low-power bi-directional analog switch specifically designed for switching High-Speed USB 2.0 signals. It is commonly used in mobile devices to multiplex a single USB port between two different functions (e.g., a modem and an application processor). ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Data Rate** | USB 2.0 High-Speed (480 Mbps) | | **Supply Voltage (Vcc)** | 2.4V to 4.4V | | **On Resistance (Ron)** | Typical 6.5 $\Omega$ | | **Bandwidth (-3dB)** | 720 MHz | | **Channel Configuration** | Low-power Dual SPDT (Single Pole Double Throw) | | **Operating Current** | < 1 $\mu$A (Ultra-low power) | | **Package Options** | 10-Lead MicroPak™ or UMLP | --- ### 2. Functional Architecture The device acts as a "traffic controller" for differential data pairs ($D+$ and $D-$). It allows a single USB connector to be routed to one of two potential USB hosts or peripherals. * **Common Pins:** $D+$ and $D-$ (connected to the physical USB port). * **Path 1:** $1D+$ and $1D-$ (typically routed to the primary processor). * **Path 2:** $2D+$ and $2D-$ (typically routed to a secondary chip or debug port). * **Control Pins:** * **S (Select):** Controls which path is active (Low = Path 1, High = Path 2). * **OE (Output Enable):** When High, it disconnects all paths (High-Impedance state). --- ### 3. Key Features & Benefits * **Signal Integrity:** With a 720 MHz bandwidth, it ensures the USB eye diagram remains open and meets USB 2.0 standards despite the added switch. * **Low Power Consumption:** Minimal battery drain, making it ideal for smartphones and tablets. * **Broad Vcc Range:** Can operate directly from a single-cell Li-ion battery. * **Over-voltage Tolerance:** The I/O pins can handle signals up to 5.25V even if the supply voltage ($V_{cc}$) is lower. --- ### 4. Typical Application Circuit In a typical design, the FSUSB40 sits between the Micro-USB/USB-C connector and the internal ICs. ```mermaid graph LR USB_Port[USB Connector] --- FSUSB40{FSUSB40 Switch} FSUSB40 --- CPU[Application Processor] FSUSB40 --- Modem[LTE/5G Modem] Control[GPIO] --> FSUSB40 ``` ### 5. Common Use Cases 1. **Shared USB Ports:** Using one port for both data transfer and firmware debugging. 2. **Dual Processors:** Switching the USB data lines between a main SoC and a standalone modem. 3. **Peripheral Expansion:** Connecting multiple internal USB-capable components to a single external interface.