FairchildFL103初級調整的LED照明解決方案

Fairchild公司的FL103是用于LED照明的第三代初級調整(PSR)PWM控制器,采用TRUECURRENT拓撲可使具有精密的恒流(CC)調整,并簡化LED照明電路,和通常設計或線性變壓器相比,具有更低的成本和更小的體積,其待機功耗小于30mW,主要用在LED照明和通用反激轉換器.本文介紹了FL103主要特性,方框圖, 典型應用電路圖和采用FL103M初級調整(PSR)的LED燈控制電路設計電路.

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應用:

? LED Illumination

? General Flyback Converter

圖1. FL103方框圖

圖2. FL103典型應用電路圖

采用FL103M的LED燈控制電路設計

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.

圖3. 采用FL103的LED燈電路圖

圖4. 變壓器結構圖
詳情請見:
http://www.fairchildsemi.com/ds/FL/FL103.pdf
和
http://www.fairchildsemi.com/an/AN/AN-9741.pdf