大功率白光LED恒流驱动电路系统设计

摘要

设计了一种新型LED恒流源电路.根据LED在低电流驱动时端电压与PN结温度成线性的特点,采用“低电流测压法”间接测量LED的结温,防止LED结温过高,延长LED寿命.采用LT3755为LED恒流驱动芯片简化电路,并采用无电解电容的DC/DC电路延长恒流源寿命.实验结果表明:LED恒流源电路工作稳定,效率高.%A new LED constant-current source circuit was designed. Based on the characteristic that the terminal voltage of LED was linear with the PN junction temperature with small current, PN junction temperature of LED was indirectly measured by measuring voltage at low current state to prevent the LED junction temperature from too high and to extend the LED lifetime. ASIC LT3755 of constant-current source for driving high current LED was used to simplify the design of circuit. To extend the lifetime of constant-current source circuit, the DC/DC circuit without electrolytic capacitor was adopted. The results showed that the constant-current source circuit for driving high current LED was robust and efficiently.