## Overview of the VIPER50S The **VIPER50S** is a high-performance Off-Line Switched Mode Power Supply (SMPS) Primary IC. It belongs to the VIPer (Vertical Integrated Power) family developed by STMicroelectronics. This component is unique because it combines a dedicated current mode PWM controller with a high-voltage Power MOSFET on the same silicon chip. --- ### Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Drain-Source Voltage ($V_{DS}$)** | 700V | | **Switching Frequency** | Adjustable up to 200 kHz | | **Supply Voltage ($V_{DD}$)** | 8V to 15V | | **Maximum Output Power** | Up to 50W (wide range) / 100W (European range) | | **Package Type** | PowerSO-10 (Surface Mount) | --- ### Internal Electronic Sections The device is divided into several functional blocks that manage power conversion and safety: #### 1. Power MOSFET The heart of the device is a **700V vertical Power MOSFET**. It is designed to handle high-voltage spikes during the "OFF" cycle of the power supply and provides the switching action necessary to transfer energy through the transformer. #### 2. PWM Controller This section regulates the output voltage. It uses **Current Mode Control**, which offers better line regulation and faster response to load changes compared to voltage mode control. #### 3. Protection Circuitry The VIPER50S is equipped with several built-in safety mechanisms: * **Overvoltage Protection (OVP):** Shuts down the device if the supply voltage exceeds safe limits. * **Thermal Shutdown:** Protects the IC from overheating by turning off the MOSFET if the junction temperature exceeds ~170°C. * **Short Circuit Protection:** Limits the current during a fault condition. #### 4. Startup High Voltage Current Source The chip includes internal startup circuitry that allows it to draw power directly from the rectified high-voltage DC bus to initialize, eliminating the need for an external startup resistor. --- ### Pin Configuration (PowerSO-10) | Pin Name | Function | | :--- | :--- | | **DRAIN** | Connected to the high-voltage MOSFET drain and the transformer primary. | | **SOURCE** | Ground reference for the internal control circuits and MOSFET source. | | **VDD** | Low voltage supply for the control logic. | | **COMP** | Input for the feedback loop to regulate output voltage. | | **OSC** | Connection for an external RC network to set the switching frequency. | --- ### Application Circuit Example ```mermaid graph LR AC_Input --> Rectifier Rectifier --> DC_Bus DC_Bus --> Transformer_Primary Transformer_Primary --> VIPER50S_Drain VIPER50S_Source --> Ground Feedback_Opto --> VIPER50S_Comp ``` The VIPER50S is typically used in **Flyback** or **Forward** converter topologies for applications like battery chargers, TV power supplies, and industrial adapters.