## Overview of the VIPER06HSTR The **VIPER06HSTR** is a high-performance, offline converter belonging to the VIPerPlus family by STMicroelectronics. It integrates an 800V avalanche-rugged power MOSFET with a Pulse Width Modulation (PWM) controller. It is specifically designed for low-power SMPS (Switched Mode Power Supplies). --- ### Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Drain-Source Voltage ($V_{DSS}$)** | 800 V | | **Switching Frequency** | 115 kHz | | **Maximum RDS(on)** | 30 $\Omega$ | | **Vcc Range** | 11.5 V to 23.5 V | | **Package** | SSOP10 (Small Outline Package) | | **Protections** | Thermal shutdown, OCP, OVP, SCP | --- ### Main Electronic Components (Internal) The VIPER06HSTR is an Integrated Circuit (IC) that combines several functional blocks: 1. **Power MOSFET:** An 800V rugged power transistor that acts as the primary switch. The high voltage rating allows for a simplified snubber circuit and handles spikes during turn-off. 2. **PWM Controller:** Regulates the output voltage by adjusting the duty cycle based on feedback. 3. **High Voltage Startup:** An internal high-voltage current source that charges the $V_{CC}$ capacitor during startup, eliminating the need for an external bleed resistor. 4. **Error Amplifier:** Includes a 3.3V internal reference for precise regulation. --- ### Pin Configuration and Functionality | Pin Name | Description | | :--- | :--- | | **DRAIN** | Connected to the high-voltage internal MOSFET drain and internal startup current source. | | **SOURCE** | Ground reference for the controller and source of the power MOSFET. | | **VCC** | Supply voltage for the internal control logic. Requires a bypass capacitor. | | **FB (Feedback)** | Input for the feedback loop. Usually connected to an optocoupler. | | **LIM (Limit)** | Allows setting the cycle-by-cycle current limit via an external resistor. | --- ### Functional Advantages * **Jittered Switching Frequency:** The IC incorporates frequency jittering to spread the Energy Spectrum, effectively reducing EMI (Electromagnetic Interference) emissions. * **Burst Mode Operation:** During light load or no-load conditions, the IC enters burst mode, significantly reducing power consumption (typically < 30mW at 230VAC). * **Protections:** * **Hiccup Mode:** If a short circuit occurs, the device enters a low-frequency restart cycle to prevent overheating. * **Thermal Shutdown:** Shuts down the IC if the junction temperature exceeds 150°C. --- ### Typical Application Diagram In a typical circuit, the VIPER06HSTR is used in a **Flyback** topology: 1. **Input:** Rectified AC mains (85V - 265V). 2. **Transformer:** Primay connected to DRAIN; auxiliary winding provides $V_{CC}$. 3. **Feedback:** TL431 and an optocoupler provide an isolated signal to the FB pin.