## VIPER53SPTR: High-Performance Off-Line Switched Mode Power Supply (SMPS) Primary Switcher The **VIPER53SPTR** is an integrated circuit (IC) developed by STMicroelectronics. It belongs to the VIPer family (Vertical Integrated Power Energy Re-generator) and is designed for high-efficiency primary switching applications. --- ### 1. Key Internal Electronic Components The VIPER53SPTR is a "monolithic" device, meaning it integrates several discrete power stages into a single package: | Component | Description | | :--- | :--- | | **Power MOSFET** | A high-voltage power MOSFET with a breakdown voltage of **620V**. | | **PWM Controller** | A pulse width modulator that controls the switching frequency and duty cycle. | | **Startup Circuit** | High-voltage current source that allows the IC to start up directly from the rectified mains voltage. | | **Error Amplifier** | An internal amplifier for precise voltage regulation. | | **Protection Circuitry** | Includes thermal shutdown, overcurrent protection (OCP), and overvoltage protection (OVP). | --- ### 2. Technical Specifications The device is optimized for power supplies ranging from **30W to 50W** (depending on the input voltage and cooling). | Parameter | Value | | :--- | :--- | | **Package** | PowerSO-10 (Surface Mount) | | **Drain-Source Voltage ($V_{DSS}$)** | 620V | | **Switching Frequency** | Up to 300 kHz (Adjustable) | | **Standby Power** | Meets "Blue Angel" and "Energy Star" (low power consumption) | | **Operating Supply Voltage ($V_{DD}$)** | 9V to 18V | --- ### 3. Pin Configuration and Functions The PowerSO-10 package has a specific layout to handle both high-voltage switching and low-voltage control: 1. **DRAIN**: Connected to the internal MOSFET drain; typically connected to the primary transformer winding. 2. **SOURCE**: Ground reference for the power and control circuits. 3. **VDD**: Supply voltage for the control logic. 4. **COMP**: Input for the feedback loop to regulate the output voltage. 5. **OSC**: Pin used to set the switching frequency via an external RC network. --- ### 4. Core Features * **Current Mode Control:** Provides excellent line and load regulation and simplifies the feedback loop design. * **Burst Mode Operation:** Under light load conditions, the IC enters burst mode to reduce switching losses and increase efficiency. * **Adjustable Current Limit:** The peak current of the MOSFET can be limited to protect the transformer from saturation. * **Soft Start:** Gradually increases the power at startup to prevent component stress. --- ### 5. Common Applications The VIPER53SPTR is widely used in: * **AC-DC Adapters**: For laptops and peripherals. * **Consumer Electronics**: DVD players, set-top boxes, and TV standby power supplies. * **Industrial Power Supplies**: Auxiliary power units for factory automation. ---