带补偿网络的高精度LED恒流驱动电路的设计

Design of High Precision Constant Current LED Driver Circuit with Compensation Network

为满足LED显示驱动芯片的要求,采用CSMC 0.5μm CMOS数模混合工艺,设计了LED恒流驱动电路。采用补偿网络与高精度电流镜,改善电路的瞬态响应并提高输出电流的精度。该电路可利用外接电阻调节恒流输出的大小,电流输出范围为3 mA～40 mA。利用Spectre在不同工艺角下对电路进行仿真,电源电压从4.5 V～5.5 V变化时,电流的最大变化率为1.62%;温度变化范围为-40℃～85℃时,最大温度系数为58.84×10-6,外接电压由2 V～6 V变化时,电流最大变化率为2.23%,驱动电路性能良好。

In order to meet the requirements of LED display driver chip, a constant current LED driver circuit is designed by using CSMC 0.5μm CMOS digital-analog mixed process. The circuit uses compensation network and high precision current mirror to improve transient response and inhance the accuracy of output current. It can uses external resistor to control the output current, the range of current is 3 mA to 40 mA. Simulated by Spectre with different corners,when the supply voltage changes from 4.5 V to 5.5 V, the maximum rate of current change is 1.62% ;when the temperature changes from -40 ℃ to 85 ℃, the maximum temperature coefficient of output current is 58. 84 × 10-6 ; external voltage varies from 2V to 6V, the maximum rate of current change is 2.23%, the performance of the driver circuit is fine.