The **TOP252** belongs to the **TOPSwitch-HX** family manufactured by Power Integrations. It is an integrated offline switched-mode power supply (SMPS) controller that combines a high-voltage power MOSFET, PWM control, and fault protection onto a single CMOS chip. --- ## 1. Key Technical Specifications The TOP252 is typically found in various package types (such as P, G, or M), and its power capability depends on the input voltage and thermal management. | Feature | Specification (Typical) | | :--- | :--- | | **Drain Voltage** | Up to 700V | | **Control Voltage** | -0.3V to 9V | | **Switching Frequency** | 66 kHz or 132 kHz (Selectable) | | **Soft Start** | Integrated (Approx. 17ms) | | **EcoSmart Technology** | High efficiency even at light loads | ### Power Capability Table | Package | 230 VAC ±15% (Adapter) | 85-265 VAC (Adapter) | | :--- | :--- | :--- | | **TOP252P/G** | 9 W | 6 W | | **TOP252MN** | 15 W | 9 W | --- ## 2. Pin Configuration and Functions The device simplifies design by reducing the external component count. Below is the standard pinout description for the **TOP252P/G** (DIP-8/SMD-8) packages: | Pin | Name | Description | | :---: | :--- | :--- | | **D** | **DRAIN** | High-voltage MOSFET drain pin. Internal startup current is drawn from here. | | **C** | **CONTROL** | Error amplifier and feedback current input pin for duty cycle control. | | **S** | **SOURCE** | Ground reference for the MOSFET and controller. | | **M** | **MULTI-FUNCTION** | Used for Line Overvoltage (OV), Undervoltage (UV), and Current Limit reduction. | --- ## 3. Internal Block Architecture The internal circuitry is designed for high efficiency and safety. Key blocks include: * **700V MOSFET:** High-speed power switch. * **Oscillator:** Generates the internal clock; features "Frequency Jittering" to reduce EMI. * **Gate Driver:** Controls the switching of the MOSFET. * **Protection Circuits:** * *Thermal Shutdown:* Hysteretic shutdown to prevent overheating. * *Auto-Restart:* Limits power delivery during output short-circuits or open-loop faults. * *Line Surge Protection:* Triggers via the Multi-function pin. --- ## 4. Typical Application Circuit A basic implementation involves the TOP252, a transformer, an optocoupler (for feedback), and a few passive components. ```text AC Input -> Bridge Rectifier -> Bulk Cap -> TOP252 Drain | [Transformer Primary] | TOP252 Source (GND) ``` ### Advantages 1. **Low Standby Power:** Consumes very little power when the load is disconnected. 2. **Simplified EMI Filter:** Frequency jittering allows for smaller, cheaper EMI filters. 3. **No Bias Winding Required:** Can be self-biased from the Drain, though a bias winding improves efficiency. ---