High Power Factor LED Driver Control Chip Design

With the development of social economy,people rise to the requirement of the quality of life. As the basic guarantee of people’s life,illumination electricity constant increase in the proportion of total output. In the 21 st century,energy shortage has been the focus of global attention, all countries in the world in the focus on the development of green lighting. LED to its energy saving、high efficiency、long life、safety advantages obtained rapid development in recent years. Due to the height of the LED current to voltage sensitivity and LED high temperature sensitivity,need to design a special LED driver control IC to control the current through LED. Power factor correction technology can restraint the input current waveform distortion,and reduce the harmonic component,thereby meeting the increasingly stringent requirements of power factor and the harmonic content. Therefore,the high efficiency with PFC function LED driver control IC design has become one of the research focus of lighting marker.The thesis designed a primary-side-control and high power factor LED driver control IC targeted flyback converter. As a result of the primary feedback control, thus opto-coupler and TL431 are not required,reducing the number of components and the cost of peripheral applications. the controller in BCM operation can guarantee the energy has been released completely from transformer when power MOSFET will turn on again,which greatly reduces the switch turn-on loss, not only improving the conversion efficiency but limiting the IC temperature. Average current control PFC technology force the input current to change following the input voltage by adjusting the power MOSFET conduction time. The chip integrates great protection coverage including VCC under voltage lockout,VCC over voltage protection,CS open circuit protection,over temperature protection,output open/short circuit protection,etc,can effectively guarantee the security of LED driver.The thesis is based on Episil 1.0μm 5V/40 V Bi CMOS process,the entire circuit has been verified. The test results are as follows: its start current is only 35 u A,the operating current is 1.6m A. In 12 W system,Vac=130V,power factor is 0.982,the system efficiency is 88.82%;Vac=220V,power factor is 0.933,the system efficiency is 88.76%.All these data indicate that the proposed high power factor LED driver controller could meet the requirements.