## Overview of the HVLED007T The **HVLED007T** is a high-performance current-mode PFC (Power Factor Correction) controller specifically designed for LED lighting applications. It is part of STMicroelectronics' family of controllers and is optimized for high-power, high-efficiency AC-DC LED drivers. --- ### Key Technical Specifications | Feature | Description | | :--- | :--- | | **Topology** | Transition Mode (TM) Boost PFC | | **Supply Voltage (Vcc)** | Up to 19V | | **Operating Current** | < 2.5 mA (Very low power consumption) | | **Protection Features** | OVP, OCP, Open Loop, Thermal Shutdown | | **Package** | SO-8 (Small Outline 8-pin) | | **Frequency** | Variable (Transition Mode) | --- ### Internal Functional Blocks The HVLED007T integrates several sophisticated electronic sections to manage power efficiently: 1. **Transition Mode Control**: Unlike fixed-frequency controllers, the HVLED007T operates at the boundary between continuous and discontinuous conduction modes. This reduces switching losses and EMI. 2. **Multiplier Block**: This internal circuit processes the rectified mains voltage sense signal to ensure the input current follows the sinusoidal shape of the input voltage, achieving a **Power Factor (PF) > 0.95**. 3. **Zero Current Detection (ZCD)**: A dedicated pin monitors the inductor demagnetization to trigger the next switching cycle at the exact moment the current hits zero. 4. **Error Amplifier**: An internal high-gain transconductance amplifier compares the output feedback against an internal precision reference (typically 2.5V). --- ### Pin Configuration and Functionality | Pin # | Name | Function | | :---: | :--- | :--- | | 1 | **INV** | Inverting input of the error amplifier. Used for output voltage feedback. | | 2 | **COMP** | Output of the error amplifier. Compensation network is connected here. | | 3 | **MULT** | Input for the main voltage multiplier to track the AC waveform. | | 4 | **CS** | Current Sense input for cycle-by-cycle overcurrent protection. | | 5 | **ZCD** | Zero Current Detection input to ensure TM operation. | | 6 | **GND** | Ground. | | 7 | **GD** | Gate Driver output to drive the external Power MOSFET. | | 8 | **VCC** | Supply voltage for the IC. | --- ### Application Example: Typical Schematic Context In a typical circuit, the HVLED007T acts as the "brain" of a boost converter: ```mermaid graph LR AC_Input --> Bridge_Rectifier Bridge_Rectifier --> Inductor Inductor --> MOSFET HVLED007T -- Drives --> MOSFET MOSFET --> Diode Diode --> LED_Load ``` ### Main Advantages * **THD Optimization**: Specially designed circuitry reduces Total Harmonic Distortion (THD) even at light loads. * **Efficiency**: By switching at zero current, it minimizes stress on the MOSFET and improves thermal performance. * **Cost-Effective**: Requires a minimal number of external components to create a compliant LED driver.