## Overview of the VIPER53DIP-E The **VIPER53DIP-E** is an off-line switched-mode power supply (SMPS) primary switcher. Developed by STMicroelectronics, it belongs to the VIPer™ 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 VIPER53DIP-E is more than just a transistor; it is an Integrated Circuit (IC) containing several functional blocks: | Component | Function | | :--- | :--- | | **Power MOSFET** | A high-voltage (620V) transistor that handles the actual switching of the transformer primary. | | **PWM Controller** | Regulates the output voltage by adjusting the Duty Cycle based on feedback. | | **Startup High Voltage Source** | Internal circuitry that allows the chip to start without an external bias resistor, saving energy. | | **Error Amplifier** | Compares feedback to a reference to maintain a stable output voltage. | | **Protection Circuitry** | Includes Over-Temperature, Over-Voltage, and Short-Circuit protection. | --- ### 2. Pin Configuration (DIP-8 Package) The device is housed in a Dual In-line Package (DIP-8). Below are the primary pin functions: | Pin Name | Function | Description | | :--- | :--- | :--- | | **DRAIN** | Power Output | Connected to the primary winding of the transformer. | | **SOURCE** | Power Ground | Ground reference for the high voltage MOSFET and internal control. | | **VDD** | Supply Voltage | Supply pin for the internal control circuits (usually 9V to 18V). | | **COMP** | Feedback Input | Used for loop compensation and setting the peak current limit. | | **OSC** | Oscillator | Defines the switching frequency (up to 300kHz) using an external RC network. | --- ### 3. Technical Specifications | Parameter | Value | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 620 V | | **Switching Frequency** | Up to 300 kHz (Adjustable) | | **Max Power Output** | ~30W (Wide range) / ~50W (European range) | | **Operating Supply Voltage** | 8.4V to 19V | | **Standby Power Consumption** | Very Low (< 100mW in Burst Mode) | --- ### 4. Typical Application Circuit In a standard Flyback converter, the VIPER53DIP-E is used to convert high-voltage DC (from rectified AC) into a stable low-voltage DC. ```cpp // General Operation Logic: 1. AC Input -> Bridge Rectifier -> High Voltage DC. 2. VIPer53 Internal Startup Source charges VDD Capacitor. 3. PWM Controller starts switching the Power MOSFET. 4. Energy transfers through the Transformer. 5. Secondary circuit provides feedback to the COMP pin (via Optocoupler). 6. VIPer53 adjusts Pulse Width to maintain regulation. ``` --- ### 5. Unique Features * **Burst Mode:** Under light load conditions, the IC enters "Burst Mode" to reduce switching losses and improve efficiency (Green Mode). * **Adjustable Current Limit:** The peak current can be set externally to protect the transformer from saturation. * **Soft Start:** Reduces stress on components during the initial power-up phase.