## Overview of the VIPER53E The **VIPER53E** is a high-performance Off-Line Switched Mode Power Supply (SMPS) Primary Switch. Developed by STMicroelectronics, it belongs to the VIPer (Vertical Intelligent Power) family, which integrates a dedicated current mode PWM controller with a high-voltage Power MOSFET on the same silicon chip. --- ### 1. Key Internal Components The VIPER53E is composed of several critical electronic blocks that allow it to function as a complete power conversion solution: | Component | Description | | :--- | :--- | | **Power MOSFET** | An 800V breakdown voltage MOSFET that handles the high-voltage switching. | | **PWM Controller** | A pulse-width modulation circuit that regulates the duty cycle based on feedback. | | **Start-up Current Source** | High-voltage internal circuitry that provides initial power to the chip before the auxiliary winding takes over. | | **Error Amplifier** | Compares the output feedback to an internal reference to maintain voltage stability. | | **Protection Circuitry** | Includes Over-Temperature, Over-Voltage, and Over-Current protection mechanisms. | --- ### 2. Technical Specifications Below are the typical electrical characteristics for the VIPER53E: | Parameter | Value | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V (Max) | | **Switching Frequency** | Up to 300 kHz (Adjustable) | | **Peak Drain Current ($I_{Dlim}$)** | 2.0 A (Approx) | | **Supply Voltage ($V_{DD}$)** | 8.4 V to 19 V | | **Package Types** | DIP-8 or PowerSO-10 | --- ### 3. Pin Configuration (DIP-8) | Pin Number | Name | Function | | :---: | :--- | :--- | | 1-2 | **SOURCE** | Ground reference for the internal control circuit and MOSFET source. | | 3 | **VDD** | Supply voltage for the control logic and gate driver. | | 4 | **COMP** | Input for the feedback loop (compensation) to regulate the output. | | 5 | **OSC** | Connection for an external RC network to set the switching frequency. | | 6-7-8 | **DRAIN** | High-voltage MOSFET drain connection; connects to the transformer primary. | --- ### 4. Distinctive Features * **Burst Mode Operation:** Under light load conditions, the device enters "Burst Mode" to reduce power consumption and improve efficiency (Standby mode). * **Adjustable Current Limit:** The peak current can be adjusted via an external resistor, allowing for flexible design based on power requirements. * **Primary Sensing:** It supports regulation from the primary side, potentially eliminating the need for an optocoupler in certain low-cost designs. --- ### 5. Application Example (Simplified) ```c /* Typical Design Flow for VIPER53E */ 1. Input Rectification (AC to DC Bridge) 2. Bulk Capacitor (Smoothing) 3. VIPER53E Switch (High-side) -> Transformer Primary 4. Feedback Loop (Optocoupler/TL431) -> COMP Pin 5. Secondary Rectification (Schottky Diode) -> DC Output ```