The **VIPER16HD** is a high-performance offline converter part of the VIPerPlus family from STMicroelectronics. It integrates an 800V avalanche-rugged power MOSFET with a Pulse Width Modulation (PWM) controller. ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V | | **Switching Frequency** | 115 kHz (Fixed) | | **Supply Voltage Range ($V_{DD}$)** | 11.5 V to 23.5 V | | **Max Peak Current ($I_{Dlim}$)** | 400 mA | | **Standby Power Consumption** | < 30 mW at 265 $V_{AC}$ | --- ### 2. Main Internal Components The VIPER16HD simplifies Switch Mode Power Supply (SMPS) design by integrating several discrete functions into a single 7-pin or 8-pin package: * **800V Power MOSFET:** The high voltage rating allows for a high "reflected voltage" and the use of smaller, cheaper snubbers, providing a safety margin against grid spikes. * **High Voltage Startup:** It features an internal high-voltage current source that charges the $V_{DD}$ capacitor during startup, eliminating the need for external bleeder resistors. * **PWM Controller:** A current-mode controller that manages the switching cycles based on the feedback signal. * **Jittering Circuit:** It incorporates frequency jittering to spread the Energy of Electromagnetic Interference (EMI), reducing the cost of input filters. --- ### 3. Pin Configuration (Typical DIP-7/SO-16) | Pin Name | Function | Description | | :--- | :--- | :--- | | **GND** | Ground | Reference ground for the control section. | | **V_DD** | Supply Voltage | Supply for the internal control logic; requires a bypass capacitor. | | **CONT** | Control | Used to adjust the current limit or for compensation. | | **FB** | Feedback | Input for the feedback loop (usually connected to an optocoupler). | | **DRAIN** | Drain | Connected to the internal MOSFET drain and the transformer primary. | --- ### 4. Protection Features The VIPER16HD is designed with "ruggedness" in mind, including several automated safety layers: 1. **Hysteretic Thermal Shutdown:** Shuts down the IC if the junction temperature exceeds 150°C. 2. **Overload Protection (OLP):** Limits power if the output is shorted or overloaded. 3. **Soft-Start:** Gradually increases the current limit during power-up to reduce stress on components. 4. **Open Loop Protection:** Prevents voltage runaway if the feedback trace is broken. --- ### 5. Application Circuit Example The VIPER16HD is typically used in non-isolated buck converters or isolated flyback converters. ```c // Typical Flyback Operation Logic Input AC -> Rectifier Bridge -> Bulk Cap -> VIPER16HD (Drain) -> Transformer Primary -> Feedback via Optocoupler -> FB Pin ```