High Power Led Lighting Driver Circuit Design

LED lighting as the next generation of lighting technology with its energy saving, environmental protection and other unique advantages catch more and more people's eyes. In advocating "low-carbon and energy-saving" of today's society, governments and scientists also focus on this green lighting technology. In recent years, high-power LED lighting is widely used in general lighting, street lighting, solar landscape light, car headlight lighting and other different areas, showing a high-power LED lighting technology potentially huge market. For this reason, as an indispensable part of LED lighting system, LED lighting driver circuit has also been a great development.Volt-ampere characteristic of an ordinary incandescent lamp is linear, so you can simply use the ordinary voltage source (AC power) to drive. With different of the incandescent, because the volt-ampere characteristic of high-power LED is exponential, slight voltage fluctuation across the LED will result in giant current changes. If the LED's current is too large, it is very easy to make the LED load burned. To ensure the normal operation of LED load, its current must be controlled. So, the best solution is to design a dedicated drive circuit to output a constant current to drive, in this way, its current can be controlled precisely.A high-power Buck LED lighting driver circuit based on constant on-time (COT) control is proposed in this paper, the main purpose is to deliver accurate drive current for the high-power LED lighting system to enable it work safely, stably and reliably. In this paper, first, the fundamental principle of high power LED driver is analyzed, started from the LED driver control model, the advantages and disadvantages of the different control strategies are explained. Considering the actual application of LED constant current driver, the constant on-time control strategy is the best choice. Then, the paper explained in detail the structure and principle of the LED driver circuit based on constant on-time control, in addition, some important sub-module circuit in the drive circuit are analyzed and simulated to ensure the normal operation of the whole circuit. Finally, for the typical application on the current market of high-power LED lighting drive,paper also presents a set of overall circuit design parameters, and simulates the whole circuit based on 0.25μm high-voltage BCD process. Simulation results show that: the drive circuit can provide accurate constant 700mA drive current for high-power LED load, and the overall efficiency of the circuit up to 94%, that can fully meet the actual needs of real applications.