摘要
设计了一种滞环控制的带数字PWM调光的LED驱动电路,并对它进行了分析与实验。该驱动电路采用高边电流检测方案,通过设定的阈值电压限制高端检测电阻两端的电压差值,从而控制流经电感的峰值和谷值电流,以此达到控制通过LED的平均电流值。实验结果表明滞环控制的LED驱动电路稳定,且能较好地解决峰值电流控制方式下的平均电流与峰值电流不一致的问题。由于滞环控制的自稳定性,故无需额外斜坡补偿电路,相对其他控制电路结构简单。此外电路还设计了数字调光功能。通过改变PWM信号的占空比,可以改变输出电流大小,测试结果表明数字调光信号可以平滑调节输出电流的大小,调光效果好。
A LED driving circuit with digital PWM light-dimming and on the basis of hysteresis-band control technique was proposed in this paper. The scheme of high side current detection is used in this circuit. It accurately regulated average current value by the threshold voltage which limits the resistor＇s dropout voltage to realize the control to the average current going through LED by controlling the peak value current and valley current passing through inductors. The experiment results show that LED driving circuit based on hysteresis-band control technique can solve the problem that peak current is not consistent with average current and works stable. Due to the self-stability of hysteresis-band control, the circuit does non need any compen- sating circuit and its structure is more simple than other circuits. In addition, a digital light-dimming function was designed in this circuit. It can change the output current by changing the duty ratio of the PWM signal. The testing results show that the digi- tal light-dimming signal can control output current smoothly.
出处
《现代电子技术》
2013年第10期128-130,共3页
Modern Electronics Technique
关键词
LED驱动电路
滞环跟踪
峰值电流
调光
LED drive circuit
hysteresis-band control
peak current
light-dimming
