Fairchild公司的FL7733A是具有初级边稳压(PSR)技术的高度集成PWM控制器,能最大限度降低中低功率LED照明转换器的元件.所有条件下的恒流误差±3%,通用输入电压变化±1%,磁性电感变化±20%是为±1%,负载电压50%到100%变化是为±1%,输入电压80 VAC - 308 VAC,PF达0.9,并具有多种保护特性.本文介绍了FL7733A主要特性和框图,典型应用电路, 50W设计案例电路图和材料清单,以及通用输入8.4W LED驱动器电路图,材料清单和PCB设计图.

The FL7733A is a highly-integrated PWM controller with advanced Primary-Side Regulation (PSR) technique to minimize components in low-to-mid-power LED lighting converters. 

Using an innovative TRUECURRENT® technology to provide tight tolerance constant-current output, this LED driver enables designs with constant current (CC) tolerance of less than ±1% over the universal line voltage range to meet stringent LED brightness requirements.

By minimizing turn-on time fluctuation, high power factor and low THD over the universal line range are obtained in the FL7733A. An integrated high-voltage startup circuit implements fast startup and high system efficiency. During startup, adaptive feedback loop control anticipates the steady-state condition and sets initial feedback condition close to the steady state to ensure no overshoot or undershoot of LED current. The FL7733A also provides powerful protections, such as LED short / open, output diode short, sensing resistor short / open, and over-temperature for high system reliability. 

The FL7733A controller is available in an 8-pin Small-Outline Package (SOP).

FL7733A主要特性:

Performance
±3% Total Constant Current Tolerance Over All Conditions
±1% Over Universal Line Voltage Variation
±1% from 50% to 100% Load Voltage Variation
±1% with ±20% Magnetizing Inductance Variation 
Primary-Side Regulation (PSR) Control for Cost-Effective Solution without Requiring Input Bulk Capacitor and Secondary Feedback Circuitry 
Application Input Voltage Range: 80 VAC - 308 VAC
High PF of 0.9, and Low THD of 10% Over Universal Line Input Range
Fast 200 ms Start-up (at 85 VAC) using Internal High-Voltage Start-up with VDD Regulation
Adaptive Feedback Loop Control for Startup without Overshoot
System Protection
LED Short / Open Protection
Output Diode Short Protection
Sensing Resistor Short / Open Protection 
VDD Over-Voltage Protection (OVP)
VDD Under-Voltage Lockout (UVLO)
Over-Temperature Protection (OTP)
All Protections are Auto Restart (AR) 

Cycle-by-Cycle Current Limit

图1. FL7733A框图

图2. FL7733A典型应用电路图

50W设计案例材料清单:

图4. FL7733A通用输入8.4W LED驱动器外形图(顶视图)

图5. FL7733A通用输入8.4W LED驱动器外形图(底层)

通用输入8.4W LED驱动器材料清单:

图7. FL7733A通用输入8.4W LED驱动器PCB设计图(顶层)

图8. FL7733A通用输入8.4W LED驱动器PCB设计图(底层)