## Overview of the VIPER17HD The **VIPER17HD** is an offline high-voltage converter that combines an 800V avalanche-rugged power MOSFET with a Pulse Width Modulation (PWM) controller. It is specifically designed for high-performance SMPS (Switched Mode Power Supplies) and is part of the VIPerPlus family by STMicroelectronics. --- ### Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V | | **RDS(on)** | 20 $\Omega$ (Typical) | | **Switching Frequency** | 115 kHz (Fixed) | | **Max Output Power** | 7W (European/Universal) / 10W (85-265 VAC) | | **Operating Supply Voltage ($V_{CC}$)** | 8.5 V to 23.5 V | | **Standby Power** | < 30 mW at 265 VAC | --- ### Internal Electronic Blocks The VIPER17HD integrates several critical electronic functions into a single 7-pin or 8-pin package (DIP-7 or SO-16): 1. **High Voltage Startup:** An internal high-voltage current source charges the $V_{CC}$ capacitor during startup, eliminating the need for an external bleeder resistor and reducing standby power consumption. 2. **800V Power MOSFET:** The power stage is ruggedized to handle voltage spikes without needing complex snubber circuits in low-power applications. 3. **PWM Controller:** Operates in current mode control with a fixed frequency of 115 kHz. It includes **frequency jittering** to reduce EMI (Electromagnetic Interference) emissions. 4. **Feedback Control (FB Pin):** Uses a transconductance error amplifier to regulate the output voltage, typically via an optocoupler. --- ### Protection Features The device is heavily protected against electrical faults, making it highly reliable for consumer electronics: * **Hysteretic Over-Temperature Protection (OTP):** Shuts down the device if the junction temperature exceeds ~150°C. * **Overload Protection (OLP):** Limits the power if the output is shorted or overloaded. * **Adjustable Over-Voltage Protection (OVP):** Monitors the auxiliary winding voltage. * **Brown-out Protection:** Disables switching if the input mains voltage falls below a certain threshold (prevents overheating during low-line conditions). --- ### Pin Configuration (DIP-7 Package) ```markdown 1. GND - Ground / Source of the MOSFET 2. VCC - Supply voltage for the control logic 3. CONT - Control pin for settling OVP/Brown-out thresholds 4. FB - Feedback input for regulation 5. BR - Brown-out sense pin 6. (N/A) - Missing pin for high voltage clearance 7, 8. DRAIN - Connection to the Transformer primary ``` --- ### Common Applications * Power supplies for household appliances (Washing machines, refrigerators). * LED lighting drivers. * Auxiliary power supplies for industrial equipment. * Adapters for tablets and set-top boxes.