The **VIPER28LN** is a high-voltage converter from the VIPerPlus family by STMicroelectronics. It integrates an 800V avalanche-rugged power MOSFET with PWM current mode control in a single package, specifically designed for offline Switch Mode Power Supplies (SMPS). --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V | | **Operating Frequency** | 60 kHz (Fixed) | | **Peak Drain Current ($I_{Dlim}$)** | 0.8 A | | **Max Duty Cycle** | 70% to 80% | | **Package Type** | DIP-7 / SO-16N | --- ### 2. Core Electronic Features The device is highly integrated to reduce the Bill of Materials (BOM) for power converters. Key internal blocks include: * **Integrated Power MOSFET:** The 800V rating allows for a wide input voltage range and provides a high safety margin against voltage spikes (surges). * **PWM Controller:** Uses current mode control to provide excellent line and load regulation. * **High Voltage Startup:** It features an internal high-voltage current source for startup, eliminating the need for external startup resistors. * **Frequency Jittering:** The switching frequency is modulated (jittered) to reduce EMI emissions, allowing for smaller and cheaper input filters. --- ### 3. Protection Mechanisms The VIPER28LN includes a robust suite of protection features to ensure circuit longevity: 1. **Hiccup Mode:** If a short circuit occurs, the device enters a low-power "hiccup" state to prevent overheating. 2. **Thermal Shutdown:** Automatically turns off the IC if the junction temperature exceeds $150^\circ C$. 3. **Overvoltage Protection (OVP):** Protects the load if the feedback loop fails. 4. **Soft-Start:** Gradually increases the current limit during power-up to reduce stress on components. --- ### 4. Typical Application Circuit In a standard Flyback converter configuration, the VIPER28LN manages the primary side switching. ```mermaid graph LR Input[AC Mains] --> Rect[Rectifier/Filter] Rect --> VIPER[VIPER28LN] VIPER --> Trans[Transformer] Trans --> Output[DC Output] Output --> Opto[Optocoupler Feedback] Opto --> VIPER ``` ### 5. Common Use Cases * **Home Appliances:** Power supplies for washing machines, refrigerators, and ovens. * **Adapters:** AC-DC wall adapters for consumer electronics. * **Lighting:** LED driver power supplies. * **Industrial:** Auxiliary power supplies for PLC and industrial controllers. ---