A New LED Driver Based On Buck Structure With Built-in Temperature Control

In recent years, with the continuous improvement of new materials and process technology, LED luminous efficiency has achieved a rapid growth, while its cost decline constantly, thus LED becomes widely used in lighting occasions. At the same time, along with the rapid development of LED industry, LED driver circuit has also made great strides.Combined with domestic and international research status of mainstream LED driver, this paper proposes Buck Converter Design for Constant-Current LED Driver with Independent Temperature Compensation. The main research contents and innovations are as follows:1、There is serious heat-generating phenomenon in High-power LED lighting. So this paper adds independent temperature compensation circuit to the driver. It utilizes bandgap reference to produce positive-temperature characteristic current, and turns to a pulse signal with duty cycle related to sense ambient temperature without external temperature sensor.2、This paper finish the design and simulation of the main modules inside the driver, including bandgap reference, PWM comparator, error amplifier, clock circuit, independent temperature compensation circuit and Self-Lift driver circuit. Self-Lift driver circuit takes advantage of Self-Lift technique to raise the gate control voltage of power switch, and manage to overcome the power source circuit floating shortcomings, making the power MOSFET being able to work in linear region.3、This paper appends current inner feedback on the basis of current outer feedback ring for the weak points of traditional voltage-mode PWM feedback control. It can not only improve the output voltage response, shorten steady-up time, but also significantly reduce the current ripple to improve the current accuracy. Unlike current-mode PWM feedback control, the structure doesn’t need to add slope compensation, and in essence, it is an improved structure of voltage-controlled mode.