The **PSM03A-050-R** is a compact, wall-mount AC/DC switching power supply manufactured by **Phihong**. It is commonly used for charging small portable electronics, powering network interfaces, or as a reliable 5V power source for microcontrollers. --- ## 1. Key Technical Specifications The following table highlights the primary electrical and mechanical characteristics of the device: | Feature | Specification | | :--- | :--- | | **Input Voltage Range** | 90V to 264V AC (Universal) | | **Output Voltage** | 5V DC | | **Output Current** | 0.6A (600mA) | | **Total Power** | 3 Watts | | **Efficiency** | Level V (Energy Star Compliant) | | **Plug Type** | Fixed US (2-Blade) | | **Output Connector** | 2.1mm x 5.5mm Center Positive | | **Ripple & Noise** | 100mV p-p Max | --- ## 2. Internal Electronic Design As a "Switching Mode Power Supply" (SMPS), the PSM03A-050-R uses a high-frequency switching regulator to convert power efficiently. ### Primary Components * **Input Rectifier & Filter:** Converts the incoming AC voltage to a high-voltage DC. It includes a bridge rectifier and electrolytic capacitors to smooth the signal. * **Switching Controller (IC):** A small integrated circuit that pulses the energy into the transformer. It monitors the output to ensure the voltage stays exactly at 5V. * **High-Frequency Transformer:** Provides **galvanic isolation**, ensuring that the high-voltage AC side is physically and electrically separated from the low-voltage DC side for safety. * **Schottky Diode:** Rectifies the high-frequency AC from the transformer back into DC on the output side. * **Feedback Optocoupler:** Sends a signal across the isolation barrier to the controller to maintain voltage stability regardless of the load. --- ## 3. Safety and Protection Features The unit is engineered with built-in electronic safeguards to prevent damage to the connected device: 1. **Over-Voltage Protection (OVP):** Shuts down if the internal circuitry fails in a way that would cause the voltage to spike. 2. **Short Circuit Protection:** The unit will enter a "hiccup mode" if the output wires are crossed, automatically recovering once the short is removed. 3. **Over-Current Protection:** Limits the output to prevent overheating if the connected device tries to draw more than 0.6A. 4. **EMI Filtering:** Includes internal filtering to meet FCC Class B requirements, ensuring it doesn't interfere with radio or Wi-Fi signals. --- ## 4. Physical Construction * **Case Material:** Non-vented, flame-retardant plastic. * **DC Cord:** Typically features a 1.5-meter (approx. 5 feet) 24AWG or 22AWG cable. * **Polarity:** The standard configuration is **Center Positive** ($+$ inside, $-$ outside).