## Overview of the VIPER15 The **VIPER15** is a high-performance, high-voltage offline converter produced by STMicroelectronics. It belongs to the **VIPerPlus** family and integrates an 800 V tough power MOSFET with a PWM (Pulse Width Modulation) controller. It is specifically designed for SMPS (Switched Mode Power Supplies) used in home appliances and industrial systems. --- ### 1. Key Internal Components The VIPER15 is a "system-in-package" that combines several electronic stages: | Component | Description | | :--- | :--- | | **800 V Power MOSFET** | A high-voltage power transistor that handles the switching of the primary current. Its high breakdown voltage provides a safety margin against spikes. | | **PWM Controller** | Regulates the output voltage by adjusting the duty cycle based on feedback. | | **High Voltage Startup** | An internal high-voltage current source that charges the VDD capacitor, allowing the chip to start without an external bleeder resistor. | | **SenseFET** | A specialized structure inside the MOSFET used to measure the drain current accurately for current-mode control. | --- ### 2. Technical Specifications Below are the primary electrical characteristics of the VIPER15: | Feature | Specification | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V | | **Switching Frequency** | Fixed at 62 kHz (L version) or 115 kHz (H version) | | **Supply Voltage ($V_{DD}$)** | 8.5 V to 23.5 V | | **Maximum Output Power** | ~7W (Wide range Vin) to ~12W (European range Vin) | | **Standby Consumption** | < 30 mW at 265 $V_{AC}$ | --- ### 3. Protection Features The VIPER15 includes integrated circuits to protect the power supply from failure: 1. **Hysteretic Over-Temperature Protection (OTP):** Shuts down the device if the junction temperature exceeds 150°C. 2. **Overload Protection (OLP):** Limits the power delivered if the output is shorted or heavily loaded. 3. **Adjustable Overvoltage Protection (OVP):** Protects the load from voltage spikes via the CONT pin. 4. **Jittered Switching Frequency:** The chip slightly varies the switching frequency to reduce EMI (Electromagnetic Interference). --- ### 4. Typical Application Schematic In a standard Flyback converter configuration, the VIPER15 pins are utilized as follows: * **DRAIN:** Connected to the primary winding of the transformer. * **SOURCE:** Connected to the circuit ground. * **VDD:** Supply voltage for the internal control circuits, usually fed by an auxiliary winding. * **FB (Feedback):** Receives the error signal from an optocoupler to regulate the output. * **CONT (Control):** Used to adjust the current limit or set the overvoltage protection threshold. ---