The **VIPER222** is a high-performance high-voltage converter specifically designed for Switched Mode Power Supplies (SMPS). It belongs to the VIPerPlus family by STMicroelectronics and integrates an 800 V avalanche-rugged power MOSFET with PWM control logic on a single chip. --- ### ## Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V | | **Oscillator Frequency** | 30 kHz / 60 kHz / 120 kHz (Fixed versions) | | **Max Output Power** | Up to 12W (Wide range) or 18W (European range) | | **Standby Power** | < 30 mW at 230 $V_{AC}$ | | **Embedded Protections** | Thermal, Overload, Short-circuit, Overvoltage | --- ### ### Internal Architecture and Logic The device is composed of several critical internal stages that allow it to function with minimal external components: 1. **High-Voltage Startup:** It includes a high-voltage current source that charges the $V_{CC}$ capacitor during startup, eliminating the need for an external startup resistor. 2. **PWM Controller:** Manages the duty cycle based on feedback to maintain a constant output voltage. 3. **SenseFET:** Instead of using a traditional sense resistor that wastes power, it uses a "SenseFET" technology to monitor current internally. 4. **Jittering Circuit:** The switching frequency is slightly modulated (jittered) to spread the EMI (Electromagnetic Interference) energy, making it easier to comply with EMC regulations. --- ### ### Pin Configuration (SO-8 Package) | Pin Name | Description | | :--- | :--- | | **GND** | Ground and source of the internal MOSFET. | | **VCC** | Supply voltage for the internal control logic. | | **FB** | Feedback input for regulation (usually connected to an optocoupler). | | **DRAIN** | High voltage pin connected to the transformer primary winding. | --- ### ### Common Application Circuit The VIPER222 is typically used in **Flyback** or **Buck** converter topologies. Below is a simplified representation of its role in a Flyback circuit: ```mermaid graph LR Input[AC Input] --> Rect[Rectifier/Filter] Rect --> Trans[Transformer Primary] Trans --> VIPER[VIPER222 Drain] VIPER --> GND[System Ground] Opto[Optocoupler] -->|Feedback| VIPER ``` --- ### ### Protection Features * **Pulse-by-Pulse Current Limit:** Limits the peak current in the MOSFET to prevent saturation. * **Hiccup Mode:** If a short circuit occurs, the device stops switching and attempts to restart periodically, preventing overheating. * **Thermal Shutdown:** Shuts down the IC if the junction temperature exceeds ~150°C.