Design Of Three-Stage Dimming LED Driver

LED,which is a new generation of light sources,plays an important role in the field of lighting because of its environmental protection and energy saving.In recent years,the annual growth rate of LED industry has exceeded 15% in transportation,medical treatment,home furnishing,landscape and other industries.In practical application,the complexity of lighting requirements and working environment calls for the driver circuit matching LED design.The design of LED driver circuit is of great significance to improving the stability and reliability of LED display function.There is still lack in the market for dimming LED driver circuit,such as design precision,dimmer mode,etc.So in this paper,which is from a proposed three-step dimming LED lighting requirements,will be based on the working principle of the LED driver circuit and proposes the performance index and the system structure of LED driver circuit chip.And it will study and design the internal voltage regulator circuit,power on reset circuit,the bandgap reference circuit,oscillator circuit,logic control circuit and constant current drive circuit on the basis of the implementation process and the packaging forms,respectively.Then it will complete the design module circuit,system circuit function verification and process simulation.Finally,it will complete the design of chip layout of dimmed LED driver circuit,which passse DRC and LVS verification.Simulation results show that the design of the three-step dimming LED driver circuit chip has achieved working state of the switch and is controled by power supply switch,the output current can be through the external resistors REXT color temperature or brightness adjustment,under the condition of the mains input,working temperature range for-40 ℃ ~ 125 ℃,the output current typical values for 60 ma,constant current output precision is less than 4%,the switch time is less than 0.5 s.The advantage and innovation of the three-phase dimming LED driver circuit and the traditional dimming LED drive circuit lie in its constant current drive and high current accuracy.Rectifier power input,built-in JFET for voltage reduction,you can use a chip to achieve tone light two functional applications,saving circuit cost and area;No external control signal,automatic switching of working state,high reliability;The external load regulating port and REXT port can change the external load capacitance or resistance according to the environment and precision requirements.