基于高边电流检测恒流驱动LED

The Constant Current Driving For LED with High Side Current Sensing Topology

本文研究了一种采用高边电流检测的滞环控制LED恒流驱动芯片。基于0．5urn5V／18V／40VCDMOS工艺，运用Hspice工具对电路进行仿真，仿真结果显示，在4．5V一28V电源电压范围内，一40°C到＋125°C工作温度范围内，电路可为LED提供恒定的350mA驱动电流，LED驱动电流为滞环变化的三角波，最大误差为6．2％。通过调节外部信号DIM的占空比可以调节LED的亮度。

In this paper, a chip which is used in the high-side current sensing topology to drive hysteresis control LED with a constant current is studied. On the basis of the technology of 0.Sum 5V/18V/40V CDMOS, the simulation by using Hspice shows that the chip can provide a driving current of 350mA for LED within the power supply voltage range from 4.5V to 28V, with the working temperatures range from -40~C to ＋125~C. The LED driving current is of triangular waveform with the hysteresis variation and its maximum control error is less than 6.2%. The luminance of LED can be adjusted by means of regulating the duty ratio of the exter- nal signal DIM.