Design of a novel high-accuracy LED driving chip

A buck type constant-current driving chip is designed and dedicated to driving small power LED lighting. Different from the traditional peak-current control method, with constant referenced peak value and average value of the inductor current in this chip, a new method is used to stabilize the current of the load cycle by cycle. On the one hand, it improves the system's constant-current accuracy, and on the other hand, it enhances the stability of the system. In addition, the power consumption of the control circuit can be effectively reduced by the detection of the inductor current only in its rising phase. The layout of the whole driving chip is completed with TSMC 0.25um BCD process. Simulation result shows that the whole chip size is 1.16mm 0.79mm, overall power consumption of the chip is 2.6mW, system constant-current accuracy is within 3%. It can meet the requirements of driving a small power LED lighting.