PWM和可编程数字信号混合控制的白光LED驱动芯片的设计
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摘要
白光LED具有发光强度大、效率高、体积小、寿命长等优点,被认为是当前最具潜力的光源之一,已经广泛应用于手机、数码相机、MP3、数字电视、照明等大多数便携式电子产品领域。为了充分发挥其优势,需要配备良好的驱动电源。驱动白光LED,关键是要提供恒定的电流,以保证发光强度的稳定和均匀。利用升压式DC/DC转换器来驱动白光LED具有高效率、高精度、高匹配度、应用灵活等优点,是便携式应用中首选的。本文主要研究的就是用于白光LED驱动的可用PWM模拟信号或经过编程的数字信号进行亮度调节的升压式DC/DC芯片的设计。
本文首先分析了开关电源的一些关键技术,从系统的高度剖析了开关电源降低功耗、提高效率和性能的方法,并从白光LED的特性中分析了它对驱动电源的要求。在此基础上,根据芯片的设计要求,构建了芯片的整体系统结构,并对各功能模块作了明确的划分。接着,分析和设计了芯片中误差放大器电路、数字信号调节LED亮度的电路、PWM模拟信号调节LED亮度的电路、过压保护、限流保护以及热关断保护电路等,并给出了仿真结果。最后,用HSPICE对芯片进行了全局仿真:芯片启动时间只需要200μs,输出电压纹波系数仅为0.5%,中等负载下转换效率在80%以上,输出电压达到14.5V时可以实现有效的过压保护,能够实现PWM亮度调节功能,仿真结果表明设计的芯片达到了预期的要求。
As one of the most promising light sources with many advantages, such as high luminous efficiency, high luminous intensity, long life period etc, White LED has been widely applied to portable electronic appliances, such as mobile phone, digital camera, MP3, digital TV and so on. An excellent power driver for high performance White LED is essential. The main function of White LED driver is to provide constant current, and now it has become the star of power management field. Using step-up DC/DC converter to drive White LED is a major method for portable applications. The design of a step-up synchronous rectification DC/DC converter Chip, with PWM and programmable digital signal dimming control, is introduced in this thesis.
In the main part of this thesis, firstly, some key techniques to reduce power waste and to enhance performance for boost DC/DC are analyzed, and in the same time, the required feature of White LED driver is deduced from the White LED feature. Based on the design requirements of the objective IC and the key technologies which analyzed and studied before, the whole chip’s architecture is constructed and the sub-circuits’function are defined. And then, some sub-circuits such as error amplifier, digital dimming control unit, PWM dimming control module, over voltage protection circuit, current limit circuit and thermal shutdown circuit are then studied in details. Finally, the whole chip simulation results by HSPICE are given: the start-up delay attains 200μs, the output voltage ripple coefficient is only 0.5%, the efficiency is above 80% under moderate load, and the over-voltage protection and PWM luminance modulation are effective.
本文首先分析了开关电源的一些关键技术,从系统的高度剖析了开关电源降低功耗、提高效率和性能的方法,并从白光LED的特性中分析了它对驱动电源的要求。在此基础上,根据芯片的设计要求,构建了芯片的整体系统结构,并对各功能模块作了明确的划分。接着,分析和设计了芯片中误差放大器电路、数字信号调节LED亮度的电路、PWM模拟信号调节LED亮度的电路、过压保护、限流保护以及热关断保护电路等,并给出了仿真结果。最后,用HSPICE对芯片进行了全局仿真:芯片启动时间只需要200μs,输出电压纹波系数仅为0.5%,中等负载下转换效率在80%以上,输出电压达到14.5V时可以实现有效的过压保护,能够实现PWM亮度调节功能,仿真结果表明设计的芯片达到了预期的要求。
As one of the most promising light sources with many advantages, such as high luminous efficiency, high luminous intensity, long life period etc, White LED has been widely applied to portable electronic appliances, such as mobile phone, digital camera, MP3, digital TV and so on. An excellent power driver for high performance White LED is essential. The main function of White LED driver is to provide constant current, and now it has become the star of power management field. Using step-up DC/DC converter to drive White LED is a major method for portable applications. The design of a step-up synchronous rectification DC/DC converter Chip, with PWM and programmable digital signal dimming control, is introduced in this thesis.
In the main part of this thesis, firstly, some key techniques to reduce power waste and to enhance performance for boost DC/DC are analyzed, and in the same time, the required feature of White LED driver is deduced from the White LED feature. Based on the design requirements of the objective IC and the key technologies which analyzed and studied before, the whole chip’s architecture is constructed and the sub-circuits’function are defined. And then, some sub-circuits such as error amplifier, digital dimming control unit, PWM dimming control module, over voltage protection circuit, current limit circuit and thermal shutdown circuit are then studied in details. Finally, the whole chip simulation results by HSPICE are given: the start-up delay attains 200μs, the output voltage ripple coefficient is only 0.5%, the efficiency is above 80% under moderate load, and the over-voltage protection and PWM luminance modulation are effective.
引文
[1]刘行仁,薛胜薜,黄德森.白光LED现状和问题.光源与照明, 2003, 3: 4~8
[2]崔元日,潘苏予.第四代照明光源——白光LED.灯与照明, 2004, 28(2): 31~34
[3]郝宗潮,胡玉.显示屏驱动芯片的种类及应用.现代显示, 2003, 6: 48~51
[4] Keith coffey.走进数字电源新时代.世界电子元器件, 2006, 3: 16~18
[5]方偑敏.白色LED驱动器的发展概况.今日电子, 2002, 11: 42~46
[6]徐九玲,谢运祥,彭军.开关电源的新技术与发展前景.电气时代, 2003, 6: 52~55
[7]季少卫,翁继周.电流型PWM控制器在电源中的应用.电子工程师, 2004, 11: 54~55
[8] Jonathan W. Kimball, Theresa L, Patrick L. Low-Input-Voltage, Low-Power Boost Converter Design Issues. IEEE POWER ELECTRONICS LETTERS, 2004, 2(3): 96~99
[9]熊亚兰.谈谈开关电源效率及开关噪声.火控雷达技术, 2005, 34 (6): 59~62
[10] Edgar Abdoulin.同步整流改进DC-DC变换器性能.电子产品世界, 2002, 2: 33~34
[11]赵睿,张波.同步整流关键技术及其主要拓扑分析.电路与系统学报, 2004, 9(3): 100~104
[12]胡宗波,张波.同步整流器中MOSFET的双向导电特性和整流损耗研究.中国电机工程学报, 2003, 22 (3): 88~93
[13]毛兴武,许海东.在升压变换器中利用新型MOSFET减少开关损耗.电源技术应用, 2001, 2: 48~51
[14]华伟.通信开关电源的五种PWM反馈控制模式研究.通信电源技术, 2001, 6: 8~12
[15]高原,邱新芸,汪晋宽.峰值电流控制开关电源斜率补偿的研究.仪器仪表学报, 2003, 24(4): 118~120
[16] Hsu S P, Brown A, Resink L, et al. Modeling and analysis of switching dc-to-dc converters in constant-frequency current programmed mode. In Rec. IEEE Power Electron. Specialists Conf., 1979: 284-301
[17]陶平,易扬波,吴建辉.电流控制模式白光LED驱动电路的频率补偿研究.现代电子技术, 2005, 18: 106~108
[18] Mihajlovic Zoran, Lehman Brad,Sun Chunxiao. Output Ripple Analysis of Switching DC–DC Converters. IEEE, 2004, 22 (8): 1596~1611
[19]刘佐濂.驱动白光LED的升压式变换器XC9103.广州大学学报(自然科学版), 2006, 1 (5): 20~23
[20]王红义,来新泉,李玉山等.一种新颖的BUCK型DC/DC芯片的抗振铃电路.电子学报, 2006, 34(2): 361~364
[21]翁寿松.白色发光二极管及其驱动电路.电子元器件应用, 2004, 5(6): 15~17
[22] Volk K R.白光LED的恒流驱动.电子产品世界, 2003, 9: 57~58
[23] Falin Jeff. LCD显示屏的核心(WLED)供电.电子产品世界, 2004, 12: 140~142
[24] Doug Varghn. Solutions for Driving White LED.电子产品世界, 2002, 6, 50~52
[25]魏智. DC-DC转换器设计.国外电子元器件, 2001, 12: 65~67
[26]程江华,谢剑斌,丁文霞等.白光LED电源驱动电路的设计与实现.电子技术, 2005, 8: 51~54
[27]徐卿,许维胜,吴启迪.功率集成电路中过热保护电路的设计.传感器技术, 2004, 23(2): 47~49
[28]赵旭杰,陈世昌.基于MCU保护的开关电源.船电技术, 2003, 6: 26~29
[29]邓云飞,吴玉广. PWM控制器欠压锁定电路的实现.电子技术, 2003, 11: 51~53
[30] David W E, Patrick K, James L K. Soft-start control for DC/DC swiching regulators. United States patent, US6515880B1, 2004.
[31]陈卢,石秉学,卢纯等.高效率同步整流式开关电源脉宽调制芯片的实现.电子学报, 2000, 28(12): 64~68
[32] Liaw C M, Chiang S J, Lai C Y, et al. Modeling and Controller Design of a Current-Mode Controlled Converter. IEEE Transactions on Industrial Electronics, 1994, 41(2): 231~240
[33]张占松.开关电源原理设计.北京:电子工业出版社, 2000. 185 ~ 189
[34] Cheung Fai Lee, Philip K T Mok. A Monolithic Current-Mode CMOS DC-DC Converter With On-Chip Current-Sensing Technique. IEEE JOURNAL OF SOLID- STATE CIRCUITS, 2004, 39(1): 3~14
[35] Strydom J T, Wyk J D, Rooij M A. Integration of a 1-MHz Converter with Active and Passive Stages. IEEE APEC, 2001, 2: 1045– 1050
[36] Rooij M A, Strydom J T, Wyk J D, et al. Development of a 1MHz MOSFET Gate-driver for Integrated Converters. IEEE Transactions on Power Electronics,2002, 52(2): 622-629
[37] Pivit E. On Dual Control Pulse Width Modulated for Stable Operation of Switched Power Supplier. IEEE Transactions on Power Electronics, 1979, 52(5): 243 ~ 249
[38] Cheng Jun, Chen Guican. A CMOS Bandgap Reference Circuit. IEEE, 2001, 8(1): 271~273
[39] Van Staveren A, Verhoeven J M, Van Roermund H M. The design of low noise bandgap references. IEEE transactions on circuits and systems, 1996, 43(4): 290~300
[40] Bryant Brad, Kazimierczuk Marian K. Open-Loop Power-State Transfer Function Relevant Current -Mode Control of Boost PWM Converter Operation in CCM. IEEE Transactions on Circuits and Systems, 2005, 52(10): 2158 ~ 2164
[41] Behzad Razavi, Bruce A, Wooley. Design Techniques for High-speed, High-Resolution Comparators, IEEE Journal of Solid-State Circuits, 1992, 27(12): 1916~1926
[42] Sum L.Tsung, Chen Kunyui, Pan Hsienyu. A fully integrated MOSFET-C oscillator with precision amplitude control and self start-up. 1997 IEEE international symposium on circuits and systems. HongKong: 1997. 67~73
[43]朱正涌.半导体集成电路.北京:清华大学出版社, 2004. 11~13
[44]陆明.智能功率集成的核心技术—BCD集成工艺简述.华东地区第二界电源技术研讨会论文. 2002. 163~171
[45]毕查德.拉扎维.模拟CMOS集成电路设计.陈贵灿,程军,张瑞智,等(译).西安:西安交通大学出版社, 2003, 246~251
[46]刘三清,罗娟,徐维峰等. PWM型数模混合电压调节器芯片电路设计.华中理工学报, 1999, 27(1): 26~28
[47] Rechard Volk Karl. Step-up/step-down switch regulators and pulse modulation control theory. United States patent, US6087816A, 2000.
[48] Phillip E. Allen, Douglas R. Holberg. CMOS Analog Circuit Design. Second Edition. Oxford University Press Inc, 2002. 626~630
[49] Guo Yongjian, Current K. Wayne. Voltage Comparator Circuits for Multiple-Valued CMOS Logic. Proceedings of the 32nd IEEE International Symposium on Multiple-Valued Logic, 2002.
[50] Richard Frank, Denis Michel Darmon. Thermal Shutdown Circuit. US patent, US6816351A, 2004.
[2]崔元日,潘苏予.第四代照明光源——白光LED.灯与照明, 2004, 28(2): 31~34
[3]郝宗潮,胡玉.显示屏驱动芯片的种类及应用.现代显示, 2003, 6: 48~51
[4] Keith coffey.走进数字电源新时代.世界电子元器件, 2006, 3: 16~18
[5]方偑敏.白色LED驱动器的发展概况.今日电子, 2002, 11: 42~46
[6]徐九玲,谢运祥,彭军.开关电源的新技术与发展前景.电气时代, 2003, 6: 52~55
[7]季少卫,翁继周.电流型PWM控制器在电源中的应用.电子工程师, 2004, 11: 54~55
[8] Jonathan W. Kimball, Theresa L, Patrick L. Low-Input-Voltage, Low-Power Boost Converter Design Issues. IEEE POWER ELECTRONICS LETTERS, 2004, 2(3): 96~99
[9]熊亚兰.谈谈开关电源效率及开关噪声.火控雷达技术, 2005, 34 (6): 59~62
[10] Edgar Abdoulin.同步整流改进DC-DC变换器性能.电子产品世界, 2002, 2: 33~34
[11]赵睿,张波.同步整流关键技术及其主要拓扑分析.电路与系统学报, 2004, 9(3): 100~104
[12]胡宗波,张波.同步整流器中MOSFET的双向导电特性和整流损耗研究.中国电机工程学报, 2003, 22 (3): 88~93
[13]毛兴武,许海东.在升压变换器中利用新型MOSFET减少开关损耗.电源技术应用, 2001, 2: 48~51
[14]华伟.通信开关电源的五种PWM反馈控制模式研究.通信电源技术, 2001, 6: 8~12
[15]高原,邱新芸,汪晋宽.峰值电流控制开关电源斜率补偿的研究.仪器仪表学报, 2003, 24(4): 118~120
[16] Hsu S P, Brown A, Resink L, et al. Modeling and analysis of switching dc-to-dc converters in constant-frequency current programmed mode. In Rec. IEEE Power Electron. Specialists Conf., 1979: 284-301
[17]陶平,易扬波,吴建辉.电流控制模式白光LED驱动电路的频率补偿研究.现代电子技术, 2005, 18: 106~108
[18] Mihajlovic Zoran, Lehman Brad,Sun Chunxiao. Output Ripple Analysis of Switching DC–DC Converters. IEEE, 2004, 22 (8): 1596~1611
[19]刘佐濂.驱动白光LED的升压式变换器XC9103.广州大学学报(自然科学版), 2006, 1 (5): 20~23
[20]王红义,来新泉,李玉山等.一种新颖的BUCK型DC/DC芯片的抗振铃电路.电子学报, 2006, 34(2): 361~364
[21]翁寿松.白色发光二极管及其驱动电路.电子元器件应用, 2004, 5(6): 15~17
[22] Volk K R.白光LED的恒流驱动.电子产品世界, 2003, 9: 57~58
[23] Falin Jeff. LCD显示屏的核心(WLED)供电.电子产品世界, 2004, 12: 140~142
[24] Doug Varghn. Solutions for Driving White LED.电子产品世界, 2002, 6, 50~52
[25]魏智. DC-DC转换器设计.国外电子元器件, 2001, 12: 65~67
[26]程江华,谢剑斌,丁文霞等.白光LED电源驱动电路的设计与实现.电子技术, 2005, 8: 51~54
[27]徐卿,许维胜,吴启迪.功率集成电路中过热保护电路的设计.传感器技术, 2004, 23(2): 47~49
[28]赵旭杰,陈世昌.基于MCU保护的开关电源.船电技术, 2003, 6: 26~29
[29]邓云飞,吴玉广. PWM控制器欠压锁定电路的实现.电子技术, 2003, 11: 51~53
[30] David W E, Patrick K, James L K. Soft-start control for DC/DC swiching regulators. United States patent, US6515880B1, 2004.
[31]陈卢,石秉学,卢纯等.高效率同步整流式开关电源脉宽调制芯片的实现.电子学报, 2000, 28(12): 64~68
[32] Liaw C M, Chiang S J, Lai C Y, et al. Modeling and Controller Design of a Current-Mode Controlled Converter. IEEE Transactions on Industrial Electronics, 1994, 41(2): 231~240
[33]张占松.开关电源原理设计.北京:电子工业出版社, 2000. 185 ~ 189
[34] Cheung Fai Lee, Philip K T Mok. A Monolithic Current-Mode CMOS DC-DC Converter With On-Chip Current-Sensing Technique. IEEE JOURNAL OF SOLID- STATE CIRCUITS, 2004, 39(1): 3~14
[35] Strydom J T, Wyk J D, Rooij M A. Integration of a 1-MHz Converter with Active and Passive Stages. IEEE APEC, 2001, 2: 1045– 1050
[36] Rooij M A, Strydom J T, Wyk J D, et al. Development of a 1MHz MOSFET Gate-driver for Integrated Converters. IEEE Transactions on Power Electronics,2002, 52(2): 622-629
[37] Pivit E. On Dual Control Pulse Width Modulated for Stable Operation of Switched Power Supplier. IEEE Transactions on Power Electronics, 1979, 52(5): 243 ~ 249
[38] Cheng Jun, Chen Guican. A CMOS Bandgap Reference Circuit. IEEE, 2001, 8(1): 271~273
[39] Van Staveren A, Verhoeven J M, Van Roermund H M. The design of low noise bandgap references. IEEE transactions on circuits and systems, 1996, 43(4): 290~300
[40] Bryant Brad, Kazimierczuk Marian K. Open-Loop Power-State Transfer Function Relevant Current -Mode Control of Boost PWM Converter Operation in CCM. IEEE Transactions on Circuits and Systems, 2005, 52(10): 2158 ~ 2164
[41] Behzad Razavi, Bruce A, Wooley. Design Techniques for High-speed, High-Resolution Comparators, IEEE Journal of Solid-State Circuits, 1992, 27(12): 1916~1926
[42] Sum L.Tsung, Chen Kunyui, Pan Hsienyu. A fully integrated MOSFET-C oscillator with precision amplitude control and self start-up. 1997 IEEE international symposium on circuits and systems. HongKong: 1997. 67~73
[43]朱正涌.半导体集成电路.北京:清华大学出版社, 2004. 11~13
[44]陆明.智能功率集成的核心技术—BCD集成工艺简述.华东地区第二界电源技术研讨会论文. 2002. 163~171
[45]毕查德.拉扎维.模拟CMOS集成电路设计.陈贵灿,程军,张瑞智,等(译).西安:西安交通大学出版社, 2003, 246~251
[46]刘三清,罗娟,徐维峰等. PWM型数模混合电压调节器芯片电路设计.华中理工学报, 1999, 27(1): 26~28
[47] Rechard Volk Karl. Step-up/step-down switch regulators and pulse modulation control theory. United States patent, US6087816A, 2000.
[48] Phillip E. Allen, Douglas R. Holberg. CMOS Analog Circuit Design. Second Edition. Oxford University Press Inc, 2002. 626~630
[49] Guo Yongjian, Current K. Wayne. Voltage Comparator Circuits for Multiple-Valued CMOS Logic. Proceedings of the 32nd IEEE International Symposium on Multiple-Valued Logic, 2002.
[50] Richard Frank, Denis Michel Darmon. Thermal Shutdown Circuit. US patent, US6816351A, 2004.