摘要：  本文介绍了FL103主要特性，方框图， 典型应用电路图和采用FL103M初级调整(PSR)的LED灯控制电路设计电路.

关键字：  PWM控制器，  待机功耗，  反激转换器

Fairchild公司的FL103是用于LED照明的第三代初级调整(PSR)PWM控制器，采用TRUECURRENT拓扑可使具有精密的恒流(CC)调整，并简化LED照明电路，和通常设计或线性变压器相比，具有更低的成本和更小的体积，其待机功耗小于30mW，主要用在LED照明和通用反激转换器.本文介绍了FL103主要特性，方框图， 典型应用电路图和采用FL103M初级调整(PSR)的LED灯控制电路设计电路.

FL103: Primary-Side-Regulation PWM Controller for LED Illumination

This third-generation Primary-Side-Regulation (PSR) and highly integrated PWM controller provides features to enhance the performance of LED illumination.

The proprietary topology， TRUECURRENT， enables precise CC regulation and simplified circuit for LED illumination applications. The result is lower-cost and smaller LED lighting compared to a conventional design or a linear transformer.

To minimize standby power consumption， the proprietary green-mode function provides off-time modulation to linearly decrease PWM frequency under light-load conditions. Green mode assists the power supply in meeting the power conservation requirements.By using the FL103， LED illumination can be implemented with few external components and minimized cost.

FL103主要特性:

Low Standby Power: < 30mW

High-Voltage Startup

Few External Component Counts

Constant-Voltage (CV) and Constant-Current (CC) Control without Secondary-Feedback Circuitry

Green-Mode: Linearly-Decreasing PWM Frequency

Fixed PWM Frequency at 50kHz and 33kHz with Frequency Hopping to Solve EMI Problems

Peak-Current-Mode Control in CV Mode

Cycle-by-Cycle Current Limiting

VDD Over-Voltage Protection (OVP)

VDD Under-Voltage Lockout (UVLO)

Adjustable Brownout Detector

Gate Output Maximum Voltage Clamped at 15V

Thermal Shutdown (TSD) Protection

Available in the 8-Lead SOIC Package

FL103应用:

LED Illumination

General Flyback Converter

图1. FL103方框图

图2. FL103典型应用电路图

采用FL103M的LED灯控制电路设计

Design Guideline for LED Lamp Control Using Primary-Side Regulated Flyback Converter， FL103M

Many LED lamp systems use the flyback converter topology. In applications where precise output current regulation is required， current sensing in the secondary side is always necessary， which results in additional sensing loss.

For power supply designers struggling to meet increasing regulatory pressures， the output current sensing is a daunting design challenge.

Primary-Side Regulation (PSR) for power supplies can be an optimal solution for compliance and cost in LED lamp systems. Primary-side regulation controls the output voltage and current precisely with information in the primary side of the LED lamp controller only. This removes the output current sensing loss and eliminates secondary-feedback circuitry. This facilitates a higher efficiency power supply design without incurring tremendous costs. Fairchild’s PWM PSR controller FL103M simplifies meeting tighter efficiency requirements with few external components.

This application note presents design considerations for LED lamp systems employing Fairchild Semiconductor components. It includes designing the transformer and output filter， selecting the components， and implementing constant-current control. The step-by-step procedure completes a power supply design. The design is verified through an experimental prototype converter using FL103.

Figure 3 shows the typical application circuit for an LED lamp using FL103M.

图3. 采用FL103的LED灯电路图

图4. 变压器结构图