## Overview of the VIPER11 The **VIPER11** is a high-voltage converter from STMicroelectronics’ VIPerPlus family. It is specifically designed for smart, efficient, and compact Switched Mode Power Supplies (SMPS). It integrates an 800 V avalanche-rugged MOSFET with a PWM controller in a single package (typically SSOP10). --- ### 1. Key Internal Components The device consists of several critical electronic blocks that manage power conversion and protection: | Component | Description | | :--- | :--- | | **800 V Power MOSFET** | A high-voltage power switch that handles the primary current. Its high breakdown voltage allows for a simplified input filter and robust operation against line surges. | | **PWM Controller** | Manages the switching frequency and duty cycle based on feedback to maintain constant output voltage. | | **High Voltage Startup** | An internal current source that draws power directly from the main line to start the IC, eliminating the need for an external startup resistor. | | **SenseFET** | A specialized structure within the MOSFET used to measure the drain current accurately for current-mode control. | --- ### 2. Technical Specifications Below are the primary electrical characteristics of the VIPER11 series: | Parameter | Specification | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V (minimum) | | **Switching Frequency** | 30 kHz (L-version) or 60 kHz (H-version) | | **Supply Voltage ($V_{CC}$)** | 4.5 V to 30 V | | **Typical Power Output** | Up to 7 W (Wide range) / 12 W (European range) | | **Standby Consumption** | Less than 10 mW at 230 $V_{AC}$ | --- ### 3. Protection Features The VIPER11 is designed with "embedded" electronic protections to prevent circuit failure: 1. **Overvoltage Protection (OVP):** Shuts down the device if $V_{CC}$ exceeds a safe threshold. 2. **Overload Protection (OLP):** Detects if the output is drawing too much power and limits the duty cycle. 3. **Thermal Shutdown:** The IC includes a temperature sensor that turns off the MOSFET if the silicon temperature exceeds ~160°C. 4. **Pulse-by-Pulse Current Limit:** Limits the peak current in the MOSFET in every switching cycle to protect the transformer from saturation. --- ### 4. Typical Application Circuit The VIPER11 is commonly used in **Flyback** or **Buck** topologies. In a standard Flyback configuration: * **Drain Pin:** Connected to the primary winding of the transformer. * **Source Pin:** Connected to the common ground. * **FB (Feedback) Pin:** Receives the error signal from an optocoupler to regulate the output. * **$V_{CC}$ Pin:** Connected to a bypass capacitor and usually fed by an auxiliary winding after startup. --- ### 5. Main Advantages * **Energy Star Compliant:** Extremely low power consumption in no-load conditions. * **Jittered Frequency:** The switching frequency is slightly modulated (jittered) to reduce EMI (Electromagnetic Interference), allowing for smaller input filters. * **Small Footprint:** The SSOP10 package saves significant PCB space compared to discrete MOSFET/Controller solutions.