LED恒流驱动电路研究与设计

基于CSMC 0.5μm BCD工艺给出LED恒流驱动电路.利用MOS管饱和区恒流特性以及电流负反馈结构,给出三种恒流驱动方案.比较三种方案的恒流工作电压,确立最终结构.采用的方案能够有效降低恒流工作电压并实现利用外接电阻控制恒流输出的大小,驱动电流范围为14.5mA到91.5mA.驱动电流可以通过外接PWM数字信号实现输出使能控制,控制响应时间为7ns.可用于LED显示屏.通过Hspice软件进行仿真,5V的电源电压波动±10%时驱动电流波动小于1.85%.环境温度由25℃变化到85℃时驱动电流变化2.14%.外接电压由0V变化到5V,此时的驱动电流变化小于5.5%.当驱动电流为91.5mA时,恒流工作电压仅为0.38V.

Research and Design of Constant Current LED Driver Circuit

Constant current LED driver circuit was designed based on CSMC 0.5μm BCD process.Three methods were given for the constant current driver used of MOS saturation constant and current negative feedback structure.Compared the operating voltage of constant current final structure was established.It can effectively reduce the operating voltage and control the current by external resistor and this can be used for LED display.The driving current range of 14.5mA to 91.5mA and it can be enable controlled by the external PWM signal with 7ns respond time.Simulated by Hspice software,the driving current′s variance can be controlled within 1.85% when the 5V supply voltage change in ±10% and it changed 2.14% when ambient temperature changed from 25 ℃ to 85 ℃.Driving current changed less than 5.5% when external voltage varied form 0V to 5V.The operating voltage achieved only 0.38V when the current was 91.5mA.