Research And Design Of Signal Stage Power Factor Correction Chip For Led Driver

As a new light source, LED has numerous advantages over traditional light source inefficiency and longevity. With wide application of LED, there is an increasingly strictdemand for LED driver chips. The design of LED driver chips with high efficiency, highintegration, low power and high accuracy is becoming a hot issue in the field of integratedcircuit design.A high-precision, primary side feedback LED constant current control chip with thefunction of Active Power Factor Correction (APFC) is designed based on the specificprojects in this thesis. This chip is suitable for85Vac~265Vac full-scope input voltagefeedback，isolated LED constant current power. A detailed investigation on The principleof main function circuit in designed chip are detailed investigation, including VCC poweron system, bandgap reference circuit, PFC control circuit, oscillator circuits etc. Tomaintain the safety and stability of the system, a lot of protection circuits are designed inthe chip, such as under voltage lock out circuit, over voltage protection circuit, over currentprotection circuit, over temperature protection circuit, short and open circuit protection ofcurrent sampling resistance, short and open circuit protection of LED etc. The mainparameters and performance of each function module are simulated, analyzed and verifiedwith cadence software. Then the main parameters and performance of the whole circuit aresimulated and analyzed. Simulation results show that the designed chip has desirableperformance.The chip layout is designed based on high-voltage0.5um BiCMOS process. DRC andLVS are verified using calibre tool of cadence, and the circuit layout is completed. Finally,the chip is manufactured and tested. The test results show that the power factor is over0.95,efficiency is more than80%, start time is about140ms, and working current for600μA.