BUCK型DC-DC的电流检测电路设计
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摘要
大规模集成电路的飞速发展使得电子产品的体积越来越小，促使了便携式电子产品如雨后春笋一般蓬勃发展，不断添加的新特征和能力，使得电子产品变得越来越复杂，作为电子设备运作的核心——电源就面临了越来越大的挑战。DC-DC电源管理芯片的高效率，低功耗等特性使得它在便携式电子设备市场中具有不可替代的地位，因此研究并改善DC-DC的性能具有很大的意义。
除了性能要满足供电产品的要求外，电源自身的保护措施也非常重要，过流保护即是防止DC-DC因过载或输出短路造成意外损坏的防护措施之一。而电流检测又是过流保护的重中之重。本文中首先分析了传统电流检测方法的功能及优缺点，在此基础上研究并提出了一种适用于电流控制模式的降压型DC-DC芯片的高性能的电流检测电路，可以及时探知电流大小，可靠地保护芯片。
本文所设计的电流检测电路包括电流采样电路和限流电路两部分，其中，电流采样部分是检测电路可靠工作的关键所在。电流采样是利用了差分放大器两个输入端的虚短特性，将一端与功率元件连接，则另一端输入就等于相应点的电压。采样电路使用了折叠式共源共栅差分电路作为采样放大器。并使用伸缩式串接差分电路构成两级比较器对采样信号进行比较。
利用CMOS工艺设计的电路容易缩减元件尺寸，增加MOSFETs的速度，而且功耗低、制作成本也低，本文的电流检测电路就采用了0.6μm的标准CMOS工艺设计，达到了较好的性能指标。利用Hspice仿真，证明了该电流检测电路的可行性和可靠性。而且此电路也适用于升压型和降—升压型DC-DC芯片的电流检测。
The rapid development of the large-scale integration (LSI) brings forth the increasingly smaller electronics, which in turn accelerates the flourishing of portable electronics. Meanwhile the growing new features and capacities make electronics more and more complex, and this poses even greater challenges to power supply, which serves as the core of the operation of electronics. The DC-DC converters, characterized by high efficiency and low power, have won an irreplaceable position in the electronics market. Thus it is of great significance to try to study and improve the performance of DC-DC converters.
Apart from satisfying the requirements of power supply products, power supplies have to be protected in each and every way. Among all the protection measures, over-current protection is one of the most desirable one for many DC-DC converters against the accidental damages as a result of overload or short circuit. And current detecting is the key of over-current protection. After analyzing the advantages and disadvantages of the traditional detecting measures, this paper proposes to work out a current detecting circuit of high performance and suitable for the BUCK DC-DC converter in current-control-mode in order that it could detect the current in time and protect the chip effectively.
The first part of this paper introduces the background and significance of this research; the second part comes to discuss some kinds of current sensing circuits. After that, on the basis of the prior knowledge, we successfully scheme out an over-current protection circuit which includes a current sensing circuit and a current limiting circuit. The principle of current sensing is as follows: if one input of differential amplifier is connected to power elements, the input voltage at the other end would be equal to that at the matching point. This paper uses a folded cascade operational amplifier for current sensing, and a telescopic cascade operational amplifier for current limiting.
Circuits designed by CMOS technology have their competitive advantages-even smaller element size, faster speed of MOSFETs, low power consumption and low cost. So this circuit is manufactured by normal 0.6μm CMOS technology. The Hspice simulation results proved the feasibility and reliability of the circuit. And finally this circuit can also be used in the current detecting of the BOOST DC-DC converter and BUCK-BOOST DC-DC converter.
除了性能要满足供电产品的要求外，电源自身的保护措施也非常重要，过流保护即是防止DC-DC因过载或输出短路造成意外损坏的防护措施之一。而电流检测又是过流保护的重中之重。本文中首先分析了传统电流检测方法的功能及优缺点，在此基础上研究并提出了一种适用于电流控制模式的降压型DC-DC芯片的高性能的电流检测电路，可以及时探知电流大小，可靠地保护芯片。
本文所设计的电流检测电路包括电流采样电路和限流电路两部分，其中，电流采样部分是检测电路可靠工作的关键所在。电流采样是利用了差分放大器两个输入端的虚短特性，将一端与功率元件连接，则另一端输入就等于相应点的电压。采样电路使用了折叠式共源共栅差分电路作为采样放大器。并使用伸缩式串接差分电路构成两级比较器对采样信号进行比较。
利用CMOS工艺设计的电路容易缩减元件尺寸，增加MOSFETs的速度，而且功耗低、制作成本也低，本文的电流检测电路就采用了0.6μm的标准CMOS工艺设计，达到了较好的性能指标。利用Hspice仿真，证明了该电流检测电路的可行性和可靠性。而且此电路也适用于升压型和降—升压型DC-DC芯片的电流检测。
The rapid development of the large-scale integration (LSI) brings forth the increasingly smaller electronics, which in turn accelerates the flourishing of portable electronics. Meanwhile the growing new features and capacities make electronics more and more complex, and this poses even greater challenges to power supply, which serves as the core of the operation of electronics. The DC-DC converters, characterized by high efficiency and low power, have won an irreplaceable position in the electronics market. Thus it is of great significance to try to study and improve the performance of DC-DC converters.
Apart from satisfying the requirements of power supply products, power supplies have to be protected in each and every way. Among all the protection measures, over-current protection is one of the most desirable one for many DC-DC converters against the accidental damages as a result of overload or short circuit. And current detecting is the key of over-current protection. After analyzing the advantages and disadvantages of the traditional detecting measures, this paper proposes to work out a current detecting circuit of high performance and suitable for the BUCK DC-DC converter in current-control-mode in order that it could detect the current in time and protect the chip effectively.
The first part of this paper introduces the background and significance of this research; the second part comes to discuss some kinds of current sensing circuits. After that, on the basis of the prior knowledge, we successfully scheme out an over-current protection circuit which includes a current sensing circuit and a current limiting circuit. The principle of current sensing is as follows: if one input of differential amplifier is connected to power elements, the input voltage at the other end would be equal to that at the matching point. This paper uses a folded cascade operational amplifier for current sensing, and a telescopic cascade operational amplifier for current limiting.
Circuits designed by CMOS technology have their competitive advantages-even smaller element size, faster speed of MOSFETs, low power consumption and low cost. So this circuit is manufactured by normal 0.6μm CMOS technology. The Hspice simulation results proved the feasibility and reliability of the circuit. And finally this circuit can also be used in the current detecting of the BOOST DC-DC converter and BUCK-BOOST DC-DC converter.
引文
[1]Mark Gildersleeve, Hassan Pooya Forghani-zadeh, Gabriel A. Rincon-Mora. A Comprehensive Power Analysis and A Highly Efficient, Mode Hopping DC-DC Converter. ASIC 2002 Proceedings. IEEE, 2002:p153-156
[2]Gong Kunlin, Feng Quanyuan, Zhao Fanglan. A Current Sensing Circuit Used in Integrated Step-Up Converter. APMC 2005 Proceedings. IEEE, vol. 5. 2005:p4
[3]樊华．超低静态电流放大器的设计．西南交通大学硕士学位论文，2005．12：p2～3
[4]Kiat-Seng Yeo，Samir s．Rofail．低压低功耗CMOS/BiCMOS超大规模集成电路[M]．Wang-Ling Goh，周元兴等译．北京：电子工业出版社．
[5]曹会宾．用低压差线性稳压器优化开关电源设计．电子工程专辑．2007
[6]颜重光．便携产品电源芯片的应用技术．21IC中国电子网．2006
[7]程晓洁．基于低压差电源稳压器的CMOS过流保护电路设计．西南交通大学硕士学位论文．2006．03：p1～4
[8]沙占友．特种集成电源最新应用技术[M]．北京：人民邮电出版社，2000．
[9]薛学明，王志宏．稳定电源及其电路实例[M]．北京：中国铁道出版社，1990．
[10]开关电源中几种过流保护方式的比较．与非网．2007
[11]J.J. Chen, J.H. Su, H.Y. Lin, C.C. Chang, Y. Lee, T.C. Chen, H.C. Wang, K.S. Chang and P.S. Lin. Integrated Current Sensing Circuits Suitable for Step-Down DC-DC Converters. Electronics Letters 5th. Feb. 2004. vol. 40, no. 3:p200～202
[12]魏曙光，马晓军，颜南明．一种带过流保护的MOSFET管驱动电路．装甲兵工程学院学报[J]，2001，15(1)：p64～67
[13]成立，李彦旭．用于模拟电子电路输出级的限流保护新技术．电子工艺技术，2002，23(3)：p112～117
[14]廖志凌，李华，贾洪平．一种简单实用的过流检测与保护电路设计．电测与仪表[J]，2003，40(454)：p32～34
[15]曲学基，王增福，曲敬铠编著．新编高频开关稳压电源．北京：电子工业出版社，2005：p100
[16]Baker Jacob R, Li Harry W, Boyce Daivid E. CMOS circuit design, layout, and simulation. IEEE, 1997: p480～484.
[17]H. Mosmose, H. Shibata, Y. Mizutani, K. Kanzaki, and S. Kohyama. High Performance 1.0m N-Well CMOS/Bipolar Technology. Symp. VLSI Technology, Tech. Dig. 1983.
[18]周志敏，周纪海，纪爱华．模块化DC-DC实用电路[M]．北京：电子工业出版社．2004
[19]华兴经济技术情报研究所．现代电源设计大全．1991
[20]王英剑，常敏慧，何希才．新型开关电源实用技术[M]．北京：电子工业出版社．1999
[21]沙占友．新编实用数字化测量技术[M]．北京：国防工业出版社．1998
[22]沙占友等．新型单片开关电源设计与应用技术[M]．北京：电子工业出版社．2004
[23]MAXIM. DC-DC Converter Tutorial. 2000
[24]National Semiconductor Corporation. Switching Power Supply Fundamentals for the System Designer. 2004
[25]Cheung Fai Lee, Philip K. T. Mok. On Chip Current Sensing Technique for CMOS Monolithic Switch-Mode Power Converters, Circuits and Systems, ISCAS 2002, IEEE International Symposium on, vol. 5:p265-268
[26]Hassan Pooya Forghani-zadeh, Gabriel A. Rincon-Mora. Current-Sensing Techniques for DC-DC Converters. Circuits and Systems. The 45th Midwest Symposium on. IEEE, vol.2. 2002:p577～580
[27]W. Schultz. Lossless current sensing with SENSEFETs Enhances the Motor Drive. Motorola technical report. 1998
[28]S. Yuvarajan. Performance Analysis and Signal Processing in a Current Sensing MOSFET(SENSEFET). in Proc. Industry Applications Society Annual Meeting, vol.2. 1991:p1445～1450
[29]P. Givelin, M. Bafleur. On-Chip Over Current and Open Load Detection for a Power MOS High Side Switch: A CMOS Current Mode Approach. in Proc. Fifth European Conference on Power Electronics and Applications,vol.2. 1993:p197～200
[30]S. Yuvarajan, L. Wang. Power Conversion and Control using a Current Sensing MOSFET. in Proc.34th Midwest Symposium on Circuits and Systems,vol.1. 1992:p166～169
[31]H. Pooya Forghani-zadeh, and Gabriel A. Rincón-Mora. A Lossless, Accurate, Self-Calibrating Current-Sensing Technique. for DC-DC Converters. Industrial Electronics Society. IEEE, 2005:p549
[32]李建飞，徐至新，钟和清．具有恒压限流和恒流限压功能的DC-DC变换器．电力电子技术[J]．1999年，第1期：p42
[33]王纪元．模块化电源保护电路设计——谈DC-DC模块电源相关保护电路设计的问题．光电对抗与无源干扰[J]．2003年，第2期：p18
[34]张立，赵永健．现代电力电子技术[M]．北京：科学出版社，1992
[35]陈益广，王晓远．检测场效应功率晶体管饱和压降实现限流控制．电力电子技术[J]．1999年，第2期：p52
[36]Chi Yat Leung, Philip K. T. Mok, Ka Nang Leung, and Mansun Chan. An Integrated CMOS Current-Sensing Circuit for Low-Voltage Current-Mode Buck Regulator. IEEE Transactions on Circuits and Systems-Ⅱ: Express Briefs, vol. 52, no. 7, July 2005:p394-397
[37]C. F. Lee and P. K. T. Mok. A monolithic current-mode CMOS DC-DC converter with on-chip current-sensing technique. IEEE J. Solid-State Circuits, vol. 39, Jan. 2004:p3-14
[36]Phillip E．Allen，Douglas R．Holberg等著．冯军，李智群等译．CMOS模拟集成电路设计(第二版)[M]．北京：电子工业出版社，2005
[39]Paul R．Gray，Paul J．Hurst，Stephen H．Lewis，Robert G. Meyer著．张晓林等译．模拟集成电路的分析与设计(第4版)[M]．北京：高等教育出版社，2005
[40]Behzad Razavi著．陈贵灿，程军，张瑞智等译．模拟CMOS集成电路设计[M]．西安：西安交通大学出版社，2003
[41]Adel S．Sedra，Kenneth C．Smith著．周玲玲，蒋乐天，应忍冬译．微电子电路(第五版)上册[M]．北京：电子工业出版社，2006：p774～775
[42]Phillip E．Allen，Douglas R．Holberg等著．王正华，叶小琳译．CMOS模拟电路设计[M]．北京：科学出版社，1995
[43]宇量．模拟电路设计(十七)：非线形电路Converter．电子设计资源网
[44]Hspice User's Manual．Meta-Soflware．INC，1996
[45]唐勇．电流检测技术的研究与设计．西南交通大学硕士学位论文，2007．04：p27
[2]Gong Kunlin, Feng Quanyuan, Zhao Fanglan. A Current Sensing Circuit Used in Integrated Step-Up Converter. APMC 2005 Proceedings. IEEE, vol. 5. 2005:p4
[3]樊华．超低静态电流放大器的设计．西南交通大学硕士学位论文，2005．12：p2～3
[4]Kiat-Seng Yeo，Samir s．Rofail．低压低功耗CMOS/BiCMOS超大规模集成电路[M]．Wang-Ling Goh，周元兴等译．北京：电子工业出版社．
[5]曹会宾．用低压差线性稳压器优化开关电源设计．电子工程专辑．2007
[6]颜重光．便携产品电源芯片的应用技术．21IC中国电子网．2006
[7]程晓洁．基于低压差电源稳压器的CMOS过流保护电路设计．西南交通大学硕士学位论文．2006．03：p1～4
[8]沙占友．特种集成电源最新应用技术[M]．北京：人民邮电出版社，2000．
[9]薛学明，王志宏．稳定电源及其电路实例[M]．北京：中国铁道出版社，1990．
[10]开关电源中几种过流保护方式的比较．与非网．2007
[11]J.J. Chen, J.H. Su, H.Y. Lin, C.C. Chang, Y. Lee, T.C. Chen, H.C. Wang, K.S. Chang and P.S. Lin. Integrated Current Sensing Circuits Suitable for Step-Down DC-DC Converters. Electronics Letters 5th. Feb. 2004. vol. 40, no. 3:p200～202
[12]魏曙光，马晓军，颜南明．一种带过流保护的MOSFET管驱动电路．装甲兵工程学院学报[J]，2001，15(1)：p64～67
[13]成立，李彦旭．用于模拟电子电路输出级的限流保护新技术．电子工艺技术，2002，23(3)：p112～117
[14]廖志凌，李华，贾洪平．一种简单实用的过流检测与保护电路设计．电测与仪表[J]，2003，40(454)：p32～34
[15]曲学基，王增福，曲敬铠编著．新编高频开关稳压电源．北京：电子工业出版社，2005：p100
[16]Baker Jacob R, Li Harry W, Boyce Daivid E. CMOS circuit design, layout, and simulation. IEEE, 1997: p480～484.
[17]H. Mosmose, H. Shibata, Y. Mizutani, K. Kanzaki, and S. Kohyama. High Performance 1.0m N-Well CMOS/Bipolar Technology. Symp. VLSI Technology, Tech. Dig. 1983.
[18]周志敏，周纪海，纪爱华．模块化DC-DC实用电路[M]．北京：电子工业出版社．2004
[19]华兴经济技术情报研究所．现代电源设计大全．1991
[20]王英剑，常敏慧，何希才．新型开关电源实用技术[M]．北京：电子工业出版社．1999
[21]沙占友．新编实用数字化测量技术[M]．北京：国防工业出版社．1998
[22]沙占友等．新型单片开关电源设计与应用技术[M]．北京：电子工业出版社．2004
[23]MAXIM. DC-DC Converter Tutorial. 2000
[24]National Semiconductor Corporation. Switching Power Supply Fundamentals for the System Designer. 2004
[25]Cheung Fai Lee, Philip K. T. Mok. On Chip Current Sensing Technique for CMOS Monolithic Switch-Mode Power Converters, Circuits and Systems, ISCAS 2002, IEEE International Symposium on, vol. 5:p265-268
[26]Hassan Pooya Forghani-zadeh, Gabriel A. Rincon-Mora. Current-Sensing Techniques for DC-DC Converters. Circuits and Systems. The 45th Midwest Symposium on. IEEE, vol.2. 2002:p577～580
[27]W. Schultz. Lossless current sensing with SENSEFETs Enhances the Motor Drive. Motorola technical report. 1998
[28]S. Yuvarajan. Performance Analysis and Signal Processing in a Current Sensing MOSFET(SENSEFET). in Proc. Industry Applications Society Annual Meeting, vol.2. 1991:p1445～1450
[29]P. Givelin, M. Bafleur. On-Chip Over Current and Open Load Detection for a Power MOS High Side Switch: A CMOS Current Mode Approach. in Proc. Fifth European Conference on Power Electronics and Applications,vol.2. 1993:p197～200
[30]S. Yuvarajan, L. Wang. Power Conversion and Control using a Current Sensing MOSFET. in Proc.34th Midwest Symposium on Circuits and Systems,vol.1. 1992:p166～169
[31]H. Pooya Forghani-zadeh, and Gabriel A. Rincón-Mora. A Lossless, Accurate, Self-Calibrating Current-Sensing Technique. for DC-DC Converters. Industrial Electronics Society. IEEE, 2005:p549
[32]李建飞，徐至新，钟和清．具有恒压限流和恒流限压功能的DC-DC变换器．电力电子技术[J]．1999年，第1期：p42
[33]王纪元．模块化电源保护电路设计——谈DC-DC模块电源相关保护电路设计的问题．光电对抗与无源干扰[J]．2003年，第2期：p18
[34]张立，赵永健．现代电力电子技术[M]．北京：科学出版社，1992
[35]陈益广，王晓远．检测场效应功率晶体管饱和压降实现限流控制．电力电子技术[J]．1999年，第2期：p52
[36]Chi Yat Leung, Philip K. T. Mok, Ka Nang Leung, and Mansun Chan. An Integrated CMOS Current-Sensing Circuit for Low-Voltage Current-Mode Buck Regulator. IEEE Transactions on Circuits and Systems-Ⅱ: Express Briefs, vol. 52, no. 7, July 2005:p394-397
[37]C. F. Lee and P. K. T. Mok. A monolithic current-mode CMOS DC-DC converter with on-chip current-sensing technique. IEEE J. Solid-State Circuits, vol. 39, Jan. 2004:p3-14
[36]Phillip E．Allen，Douglas R．Holberg等著．冯军，李智群等译．CMOS模拟集成电路设计(第二版)[M]．北京：电子工业出版社，2005
[39]Paul R．Gray，Paul J．Hurst，Stephen H．Lewis，Robert G. Meyer著．张晓林等译．模拟集成电路的分析与设计(第4版)[M]．北京：高等教育出版社，2005
[40]Behzad Razavi著．陈贵灿，程军，张瑞智等译．模拟CMOS集成电路设计[M]．西安：西安交通大学出版社，2003
[41]Adel S．Sedra，Kenneth C．Smith著．周玲玲，蒋乐天，应忍冬译．微电子电路(第五版)上册[M]．北京：电子工业出版社，2006：p774～775
[42]Phillip E．Allen，Douglas R．Holberg等著．王正华，叶小琳译．CMOS模拟电路设计[M]．北京：科学出版社，1995
[43]宇量．模拟电路设计(十七)：非线形电路Converter．电子设计资源网
[44]Hspice User's Manual．Meta-Soflware．INC，1996
[45]唐勇．电流检测技术的研究与设计．西南交通大学硕士学位论文，2007．04：p27