The Key Technology Research On High Power Factor Primary-Side Feedback LED Lighting Contorl Drive

Nowadays the energy shortage is getting worse, energy saving has become thefocus of the concern, countries around the world start focus on the improvement ofgreen efficient lighting.LED lighting as a green light source, with its energyconservation,long lifetime, high efficiency, environment friendliness, safety andreliability,in recent years the LED technology develops rapidly. Due to characteristicsof LED, such as high temperature sensitivity and large forward voltage, speciallydesigned power management IC is needed. PFC technology can effectively restraintthe input current waveform distortion, and minimize the total harmonic distortion(THD), thereby meeting the increasingly stringent requirements of power factor andthe harmonic content. Therefore, the high efficiency with PFC function LED lightingpower supply controller chip design has become one of the research focus of domesticand foreign industry and academia.The thesis designed a primary-side-control and high power factor flyback PWMcontroller specifically targeted LED lighting.As a result of the primary side sensingand regulation, thus opto-coupler and TL431are not required, reducing the number ofcomponents and the cost of peripheral applications. Based on analog multipliertransition PFC mode greatly reduces the switch turn-on loss, improves the conversionefficiency. It provides very good power factor. The chip integrates great protectioncoverage including VCC under voltage lockout,VCC over voltage protection,Levelselectable cycle-by-cycle current limiting,over temperature protection, LED open/shortcircuit protection and gate drive output clamping for external power MOSFETprotection, etc, can effectively guarantee the security of LED power and light.The thesis is based on Episil1.0μm5V/40V BiCMOS process, the entire circuithas been verified. The test results are as follows: the designed system has a goodpower factor correction function, its start current is only5.5μA, the operating current is1.6mA,the normal operating frequency is110kHz. Vac=110V, power factor is0.9937,the system efficiency is87.60%; Vac=220V, power factor is0.9571,the systemefficiency is88.45%.All these data indicate that the proposed TM PFC converter couldmeet the requirements for low zero-crossing distortion,as well as a high efficiency.