The Design And Research Of LED River IC With A Variable Slope Compensation

According to the IC development, CAD, advanced reseaching of semiconducting material, LED lighting industry become an important direction of integrated circuit. With the flourishing of LED lamp industry, the LED power is the key technology adhibition, and as an important module of LED power,the driving IC determin the LED power performance. Therefore,the paper is committed to research and design LED driver IC.The paper according to the semiconductor-solid lighting, and expressd the effect of LED power source and driver IC. At the same time,this paper describe the isolation of DC- DC mode driver chip, on the basis of the theory of the isolation type DC- DC mode driver chip, the paper research and analysis the theory of overview structure control, feedback method, the stability and ramp compensation. On the basis of the theory of invariant slope compensation,the paper design a method of variable slope compensation, through sampling voltage of the chip power source and LED load,And turn into current. At the same time,according to the theory of pulse control cap charging current, using the chip inside-module OSC control the capacitacne charging current, and poduceing the ramp pressure which is linear related to input and output pressure.through the slop cap produce different ramp voltage,and the ramp pressure is feedbacked to chip PWM comparator module.Through this method realize the chip can output constant current, driving the LED IC.This paper designed chip inside module include BGR, LDO, oscillator, OV-protection circuit, UV-protection circuit, used to make sure the chip can realize the basic function, and variable slope compensation technology. Chip circuit design use BJT, medium voltage MOSFET of CSMC0.5μm BCD process to design the inside module of the chip module circuit, and design the chip layout.and simulating the inside_module and overall IC function. Chip in 6 V to 10 V input range, export pressure stability in 18 V, maximum peak current is 350 mA,and the chip export pressure precision is exceed 3%, the export current precision is exceed 10%. Under large duty ratio of pulse control signal, the chip export power change rate is only 3.1%, realize capacity of maintain maximum load by the variable ramp compensation.