## TOP233PN Overview The **TOP233PN** belongs to the **TOPSwitch-GX** family manufactured by Power Integrations. It is an integrated off-line switched-mode power supply (SMPS) IC that combines a high-voltage power MOSFET, PWM control, fault protection, and other control circuitry onto a single CMOS chip. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Package** | DIP-8B (Plastic Dual In-Line) | | **Drain Voltage (Max)** | 700 V | | **Output Power (230VAC)** | Up to 25 W (Adapter) / 50 W (Open Frame) | | **Output Power (85-265VAC)** | Up to 13 W (Adapter) / 20 W (Open Frame) | | **Switching Frequency** | 132 kHz (Full) / 66 kHz (Half) | | **Operating Temperature** | -40°C to 150°C (Junction) | --- ### 2. Internal Functional Blocks The TOP233PN is highly integrated to reduce external component count. Its primary internal components include: 1. **Power MOSFET:** A 700V rated MOSFET that performs the high-speed switching. 2. **Control Engine:** Includes a precision oscillator, PWM comparator, and gate driver. 3. **Protection Circuitry:** * **Hysteretic Thermal Shutdown:** Shuts down the IC if the temperature exceeds ~140°C. * **Current Limiting:** Protects the device during overload conditions. 4. **Soft-Start:** Reduces component stress by gradually increasing the duty cycle during startup. --- ### 3. Pin Configuration (DIP-8B) | Pin | Name | Description | | :--- | :--- | :--- | | **1** | **D (DRAIN)** | High-voltage MOSFET drain pin. Provides internal operating current during start-up. | | **2** | **C (CONTROL)** | Error amplifier and feedback current input pin for duty cycle control. | | **3** | **L (LINE-SENSE)** | Optional pin for overvoltage/undervoltage sensing and remote ON/OFF. | | **4** | **X (EXTERNAL CURRENT LIMIT)** | Optional pin for external current limit adjustment. | | **5** | **F (FREQUENCY)** | Selects switching frequency (Connected to SOURCE for 132kHz). | | **7, 8** | **S (SOURCE)** | Control circuit common and output MOSFET source. | --- ### 4. Typical Application Circuit The TOP233PN is commonly used in **Flyback Converter** topologies. ```mermaid graph LR AC_Input --> Rectifier Rectifier --> Transformer_Primary Transformer_Primary --> TOP233PN_Drain TOP233PN_Source --> Ground Transformer_Secondary --> Diode_Rectifier Diode_Rectifier --> DC_Output DC_Output -. Feedback .-> TOP233PN_Control ``` ### 5. Benefits of using TOP233PN * **EcoSmart Technology:** Highly efficient even at light loads, meeting global energy savings standards. * **Reduced Component Count:** Eliminates the need for external cascode components and complex start-up resistors. * **Frequency Jittering:** Reduces EMI (Electromagnetic Interference) emissions, allowing for smaller/cheaper input filters. ---