Design Of LED BUCK Driver IC With Constant-current And Adjust-frequency

LED lighting as the next generation of lighting technology with its energy saving,environmental protection and other unique advantages catch more and more people’seyes. In advocating "low-carbon and energy-saving" of today’s society, governmentsand scientists also focus on this green lighting technology. In recent years, high-powerLED lighting is widely used in general lighting, street lighting, solar landscape light, carheadlight lighting and other different areas, showing a high-power LED lightingtechnology potentially huge market. As an indispensable part of LED lightingsystem,LED lighting driver circuit has been a great development.Volt-ampere characteristic of an ordinary incandescent lamp is linear, so you cansimply use the ordinary voltage source (AC power) to drive. With different of theincandescent, because the volt-ampere characteristic of high-power LED isexponential,slight voltage fluctuation across the LED will result in giant currentchanges. 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 todrive, in this way, its current can be controlled precisely.According to the key performance of the high power LED drive circuit，the papercomparatively analyzes the different LED drive control schemes and points out theconstant on-time control strategy is the best choice. Based on CSMC0.5μ m80V BCDprocess,the paper completes the design of LED buck driver IC with constant-current andadjust-frequency. The circuit`s normal operating voltage is42V, the output current is330mA, the output voltage is28.2V. Complete the simulations of the integral circuit andthe key modules such as bandgap,comparator,timer,level-shift,driver. The keyperformance simulation data of the whole circuit and modules shows that the simulationresults meet the design requirements.Finally, complete parameters optimization design and test-result analysis of thedriver chip.Through the flow sheet after verification, packaging, testing and analysis ofthe test results,the test data and the simulation data are consistent with each other, testresults meet the design requirements. After adjusting the parameter, the ultimate goal isto make it be qualified products for market.