基于恒定开关频率DC-DC变换器的大功率LED驱动芯片  

Design of a High Power LED Driver Based on Constant Switching Frequency DC-DC Converter

作　　者：徐瑶[1] 杨维明[1] 鲍钰文[2] 

机构地区：[1]湖北大学计算机与信息工程学院,武汉430062 [2]湖北大学材料科学与工程学院,武汉430062

出　　处：《固体电子学研究与进展》2015年第1期88-93,共6页Research & Progress of SSE

摘　　要：完成了一种降压型恒流LED驱动芯片的设计。采用迟滞控制模式以提高芯片工作时的瞬态响应速度;采用电阻分压式二阶曲率补偿方法设计出低温度系数和高电源抑制比的带隙基准电路;对导通时间与关断时间电路进行设计改进,使导通时间与关断时间均与输入电压有关,且相互抵消,从而使开关频率仅由负载和外接电阻决定,保证了开关频率的稳定,且可按需求选择。采用ASMC 0.5μm BCD 60V工艺,完成芯片的设计,流片测试结果表明：芯片可在10-40V的工作电压范围内提供350mA的恒定驱动电流,纹波为70mA;在输出电流为350mA、驱动3个LED时的输出效率高达90%,且在相同负载条件下,输出电流变化时,输出效率基本不变。A chip used in the buck application to drive the white LED with a constant current is proposed in this paper.By using hysteretic control mode,the transient response speed of the chip was improved.The second-order curvature compensation circuit realized by voltage divided technology was employed to design a low temperature coefficient and high PSRRband-gap reference source.Moreover,the circuit of the on-time and off-time was modified.As a result,the ontime and off-time changed with the input voltage but cancelled out each other,so the switching frequency kept constant and optional and could be determined by the load and the external resistor.The circuit was designed and fabricated based on ASMC 0.5μm BCD 60 V process.The measurement results indicate that the chip can provide a constant driving current of 350 mA with current ripple of 70 mA for LED and within the input voltage range of 1040V.The driving efficiency can reach 90% when driving three LEDs,with the output current of 350 mA.And at the same load,its efficiency does not change with the output current.

关 键 词：恒流 开关频率 发光二极管驱动电路 大功率 效率 

分 类 号：TN433[电子电信—微电子学与固体电子学]