Fairchild 公司的FL7730是可調光的單級PFC離線LED驅動器,和傳統的TRIAC控制兼容,和無調光燈設計兼容,不需要輸入大電容和反饋電路,具有開路,短路保護,逐個周期的限流,起動電流20uA,工作電流5mA,應用電壓倒80VAC ~ 308VAC,主要用于照明.本文介紹了FL7730主要特性,方框圖以及8.4W LED照明燈主要性能指標,燈外形,PCB電路圖,材料清單和PCB元件布局圖.
This highly integrated PWM controller, FL7730MY, provides several features to enhance the performance of single-stage flyback converters. The proprietary topology, TRUECURRENT™, enables the simplified circuit design for LED lighting applications.
The FL7730 is an active Power Factor Correction (PFC) controller using single-stage flyback topology. Dimming control with no flicker is implemented by an analog sensing method. Primary-side regulation and single-stage topology reduce external components such as input bulk capacitor and feedback circuitry and minimize cost. To improve good power factor and Total Harmonic Distortion (THD), constant on-time control is utilized with internal error amplifier and a low-bandwidth compensator. Precise constant-current control regulates accurate output current, independent of input voltage and output voltage. Operating frequency is proportionally changed by output voltage to guarantee DCM operation with higher efficiency. FL7730 provides protections such as open-LED,short-LED, and over-temperature protection.
TRIAC dimming is smoothly managed by dimming brightness control without flicker. By using single-stage topology with primary-side regulation, an LED lighting board can be implemented with few external components and minimized cost. It does not require an input bulk capacitor or feedback circuitry. To implement good power factor and low total harmonic distortion, constant on-time control is utilized with an external capacitor connected to the COMI pin.
Precise constant-current control regulates accurate output current versus changes in input voltage and output voltage. The operating frequency is proportionally changed by the output voltage to guarantee Discontinuous Conduction Mode (DCM) operation with higher efficiency and simpler design. The FL7730MY provides protections such as open-LED, short-LED, and over-temperature protections. Current-limit level is automatically reduced to minimize output current and protect external components in a short-LED condition.
The FL7730MY controller is available in an 8-pin SOP package.
FL7730主要特性:
? Compatible with Traditional TRIAC Control (No need to change existing lamp infrastructure: wall switch & wire)
? Compatible with Non-Dimming Lamp Designs
? Cost-Effective Solution without Input Bulk Capacitor and Feedback Circuitry
? Power Factor Correction (PFC)
? Accurate Constant-Current (CC) Control, Independent Online Voltage, Output Voltage, Magnetizing Inductance Variation
? Line Voltage Compensation for CC Control
? Linear Frequency Control for Better Efficiency and Simple Design
? Open-LED Protection
? Short-LED Protection
? Cycle-by-Cycle Current Limiting
? Over-Temperature Protection with Auto Restart
? Low Startup Current: 20µA
? Low Operating Current: 5mA
? SOP-8 Package Available
? Application Voltage Range: 80VAC ~ 308VAC
FL7730應用:
Lighting
圖1.FL7730方框圖
LED照明燈主要性能指標:
圖2.8.4W LED燈 PCB外形圖:頂視圖
圖3.8.4W LED燈 PCB外形圖:底視圖
圖4.8.4W LED燈外形圖
圖5.8.4W LED燈電路圖
圖6.8.4W LED燈變壓器電路圖
8.4W LED燈材料清單(BOM):
圖7.8.4W LED燈PCB元件布局圖:頂層
圖8.8.4W LED燈PCB元件布局圖:底層
詳情請見:
http://www.fairchildsemi.com/an/AN/AN-FEB020H.pdf
和
http://www.fairchildsemi.com/support/referencedesign/docs/RD-L020-2.pdf
