## Overview of the SSL21083AT The **SSL21083AT** is a high-voltage Integrated Circuit (IC) designed by NXP Semiconductors. It is specifically engineered to drive LED lamps in non-isolated, high-efficiency applications. It belongs to the GreenChip™ family, focusing on low power consumption and high integration. --- ### Core Specifications | Feature | Specification | | :--- | :--- | | **Package** | SO-8 (Small Outline, 8 pins) | | **Topology** | Buck (Step-down) converter | | **Input Voltage Range** | 100 V to 230 V (AC mains) | | **Internal MOSFET** | Integrated 600 V / 5 $\Omega$ | | **Max Output Power** | Up to 15 W (depending on thermal design) | | **Efficiency** | Up to 95% | --- ### Key Electronic Functional Blocks 1. **High-Voltage Internal Power Switch**: The IC contains a built-in 600V MOSFET. This reduces the bill of materials (BOM) count because an external transistor is not required. 2. **Current Sensing**: It operates in **Boundary Conduction Mode (BCM)**. It senses the current through the inductor to ensure the MOSFET switches at the optimal time, minimizing switching losses. 3. **Start-up Circuit**: Includes an internal high-voltage start-up source, allowing the IC to power itself directly from the rectified mains voltage without needing a dedicated auxiliary winding or large start-up resistors. 4. **Protection Mechanisms**: * **Under-Voltage Lockout (UVLO):** Prevents operation if the input voltage is too low. * **Over-Temperature Protection (OTP):** Throttles or shuts down the device if it overheats. * **Short-Winding Protection (SWP):** Protects against inductor shorts. * **Over-Current Protection (OCP):** Limits the peak current to protect the LED string. --- ### Pin Configuration (SO-8) | Pin # | Name | Description | | :--- | :--- | :--- | | 1 | **VCC** | Supply voltage for the IC | | 2 | **GND** | Ground reference | | 3 | **DVDT** | Monitoring pin for the MOSFET drain voltage | | 4 | **N.C.** | Not connected | | 5 | **DRAIN** | Drain of the internal MOSFET (High Voltage) | | 6 | **DRAIN** | Drain of the internal MOSFET (High Voltage) | | 7 | **SOURCE** | Source of the internal MOSFET / Current sense input | | 8 | **ROVP** | Over-voltage protection programming pin | --- ### Typical Application Circuit Example The SSL21083AT is primarily used in **Buck configurations**. ```mermaid graph LR AC_Input --> Rectifier Rectifier --> SSL21083AT_IC SSL21083AT_IC --> Inductor Inductor --> LED_String LED_String --> Feedback_Loop ``` --- ### Design Advantages * **Space Saving:** Because the MOSFET and start-up circuitry are internal, the PCB footprint is extremely small. * **High Efficiency:** By utilizing Boundary Conduction Mode, it achieves very low switching losses. * **Cost-Effective:** Minimal external components (resistors/capacitors) are needed to complete a functional LED driver. ---