The **US203AHG-AF5-R** is a specific electronic component, typically classified as a **High-Side Power Switch** or a **Load Switch**, often used in USB power distribution and power management applications. Below is a detailed breakdown of its specifications, pin configuration, and technical features. --- ### 1. General Specifications The part is manufactured by companies like **UTC (Unisonic Technologies)**. It is designed to provide protection and controlled switching for power rails. | Feature | Specification | | :--- | :--- | | **Component Type** | Single Channel High-Side Power Switch | | **Package Type** | SOT-25 / SOT-23-5 | | **Input Voltage Range** | 2.7V to 5.5V | | **Continuous Current** | ~1.5A to 2.0A (Typical) | | **On-Resistance ($R_{DS(ON)}$)** | Low resistance (Approx. 70-100mΩ) | | **Enable Logic** | Active High or Active Low (Depending on specific suffix) | | **Protection Features** | Over-current, Short-circuit, Over-temperature | --- ### 2. Pin Configuration (SOT-25) Standard configuration for the AF5 (SOT-25) package: | Pin Number | Pin Name | Description | | :--- | :--- | :--- | | 1 | **GND** | Ground | | 2 | **VIN** | Input Voltage Supply | | 3 | **EN** | Enable Input (Controls the switch) | | 4 | **FLG** | Fault Flag (Open-drain output, indicates over-current/thermal) | | 5 | **VOUT** | Output Voltage | --- ### 3. Key Technical Features * **Current Limiting:** The device includes an internal current-limiting circuit that prevents the power supply from crashing when a heavy load or short circuit is applied to the output. * **Thermal Shutdown:** If the internal junction temperature exceeds a threshold (usually around 150°C), the switch automatically turns off to prevent permanent damage. * **Soft Start:** It features a controlled "rise time" to prevent large inrush currents that could cause voltage dips on the main power bus. * **Fault Flag (FLG):** This pin goes "Low" when a fault condition (over-current or over-temperature) is detected, allowing a microcontroller to react to the error. --- ### 4. Typical Applications This part is commonly found in: * **USB Ports:** Protecting PC motherboards or laptops from faulty USB peripherals. * **Hot-Swap Supplies:** Used in systems where modules are plugged in while power is active. * **Battery Chargers:** Acting as a safety disconnect switch. ---