Design Of High-precision Constant Current Driver Chip With Primary-side Feedback For LED

In recent years, under the trend of the energy conservation and emissions reduction and green environmental protection, as the fourth generation of electric light source, LED is gradually replace the traditional lamp source. In order to reflect the superiority of the LED, design a high efficiency high reliability of the LED chip, for the development of the LED and energy conservation is of great importance.This paper designs a high-precision constant current driver chip with primary-side feedback for LED, by setting the system working in the discontinuous inductor current mode and working cycle for transformer demagnetization time twice, and then changes the current peak based on the change of the input voltage, so as to realize constant current output characteristics, and improve the precision of the system. The chips used primary-side feedback technology without the auxiliary winding, simplifies the transformer design, save the light coupling, TL431 and special pin and at least two partial pressure resistance, reduce the cost of the system. The chip designed without the auxiliary winding, but through comparing the transformer demagnetization time is less than the minimum demagnetization of setting time, so as to determine whether the system output voltage is too high. The chip with lots of protection function, to ensure safe and reliable in the abnormal environment work.The chip is based on the 1.0μm CDMOS 5V/40 V process model, the simulation work is in Cadence software environment, using Hspice simulation tool. Through the simulation of the controller system built with a fly-back converter, knowing the chip performance indicators meet the requirements. the analysis of results prove the feasibility and correctness of theoretical analysis and design method.