## Overview of the VIPER114LSTR The **VIPER114LSTR** is a high-voltage converter belonging to the **VIPerPlus** family by STMicroelectronics. It is an integrated "Offline Converter" that combines a high-performance PWM (Pulse Width Modulation) controller with an 800V avalanche-rugged Power MOSFET. It is primarily used in **Switched-Mode Power Supplies (SMPS)** to create compact, efficient, and low-power AC-DC converters. --- ### Key Technical Specifications | Parameter | Value / Description | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V | | **Drain Peak Current ($I_{Dlim}$)** | 480 mA | | **Switching Frequency** | 60 kHz (Fixed) | | **Package Type** | SSOP10 (Surface Mount) | | **$R_{DS(on)}$** | 6 $\Omega$ (Typical) | | **Max Output Power** | ~7W (Wide Range) / ~12W (European Range) | --- ### Core Electronic Components (Internal) 1. **800V Power MOSFET**: The heart of the chip. Its high voltage rating allows the device to withstand significant voltage spikes without the need for complex snubber circuits in many designs. 2. **High-Voltage Startup Cell**: This allows the chip to start up directly from the rectified mains voltage, eliminating the need for an external startup resistor and reducing "standby" power consumption. 3. **PWM Controller**: Regulates the power delivery by adjusting the duty cycle of the MOSFET based on feedback. 4. **Error Amplifier**: Includes an integrated 1.2V reference voltage for precise regulation. 5. **Protection Circuitry**: * **Pulse-skip mode**: Reduces switching frequency at light loads to save energy. * **Overvoltage Protection (OVP)**: Protects against voltage surges. * **Thermal Shutdown**: Turns off the device if it exceeds safe operating temperatures ($150^\circ\text{C}$). --- ### Pin Configuration (SSOP10) | Pin Name | Function | | :--- | :--- | | **DRAIN** | Connected to the internal Power MOSFET drain and high-voltage startup. | | **GND** | Ground/Source connection for the MOSFET and control logic. | | **VCC** | Supply voltage for the internal control logic. | | **FB (Feedback)** | Input for the feedback loop to regulate the output voltage. | | **LIM** | Allows setting the current limit (optional via external resistor). | --- ### Typical Application Circuit The VIPER114LSTR is commonly used in **Flyback** or **Buck** converter topologies. Below is a conceptual representation of its integration: ```text AC Input -> Bridge Rectifier -> Bulk Capacitor -> VIPER114LSTR (Transformer Primary) | Feedback Loop (Optocoupler) | DC Output (Secondary Side) ``` --- ### Advantages * **Low Standby Power**: Consumes less than 10mW at 230VAC in no-load conditions. * **Safety**: Integrated frequency jittering reduces EMI (Electromagnetic Interference) emissions. * **Space Saving**: The SSOP10 package and integrated MOSFET significantly reduce the PCB footprint.