An automatic load-adaptive switching frequency selection technique for improving the light-load efficiency of a buck converter

A load-adaptive automatic switching frequency selection scheme is proposed to improve the power efficiency of a switching buck converter at light load condition. The buck converter operates in the continuous-conduction mode for heavy loading and the switching frequency is fixed at its maximum value. For light loading, the buck converter operates in the discontinuous-conduction mode and its switching frequency is automatically selected among a pre-defined set of frequencies according to the amount of the load current. The load current can be sensed indirectly by monitoring the on-time of power transistor because it is a function of the load current. With the proposed load-adaptive automatic switching frequency selection circuit, the power efficiency of a buck converter implemented in a 0.35-μm 2P4M BCDMOS technology is improved by 24.0-% when the load current load is 10-mA.

[1]  Ke-Horng Chen,et al.  Adaptive Window Control (AWC) Technique for Hysteresis DC–DC Buck Converters With Improved Light and Heavy Load Performance , 2009, IEEE Transactions on Power Electronics.

[2]  Xu Zhang,et al.  Multimode Digital Controller for Synchronous Buck Converters Operating Over Wide Ranges of Input Voltages and Load Currents , 2010, IEEE Transactions on Power Electronics.

[3]  P.L. Chapman,et al.  Improvement of light-load efficiency using width-switching scheme for CMOS transistors , 2005, IEEE Power Electronics Letters.

[4]  Thomas H. Lee,et al.  A 3MHz Low-Voltage Buck Converter with Improved Light Load Efficiency , 2007, 2007 IEEE International Solid-State Circuits Conference. Digest of Technical Papers.

[5]  F.C. Lee,et al.  Light-Load Efficiency Improvement for Buck Voltage Regulators , 2009, IEEE Transactions on Power Electronics.

[6]  Chien-Hung Tsai,et al.  Integrated single-inductor buck-boost or boost-boost DC-DC converter with power-distributive control , 2009, 2009 International Conference on Power Electronics and Drive Systems (PEDS).

[7]  Siyuan Zhou,et al.  A high efficiency, soft switching DC-DC converter with adaptive current-ripple control for portable applications , 2006, IEEE Transactions on Circuits and Systems II: Express Briefs.

[8]  F.C. Lee,et al.  A resonant MOSFET gate driver with efficient energy recovery , 2004, IEEE Transactions on Power Electronics.

[9]  Hao Min,et al.  A Multimode Digitally Controlled Boost Converter With PID Autotuning and Constant Frequency/Constant Off-Time Hybrid PWM Control , 2011, IEEE Transactions on Power Electronics.

[10]  Jian-Min Wang,et al.  A Novel Control Scheme of Synchronous Buck Converter for ZVS in Light-Load Condition , 2011, IEEE Transactions on Power Electronics.

[11]  Chi-Ying Tsui,et al.  An integrated one-cycle control buck converter with adaptive output and dual loops for output error correction , 2004 .

[12]  Hou-Ming Chen,et al.  An Exact Current-Mode PFM Boost Converter With Dynamic Stored Energy Technique , 2009, IEEE Transactions on Power Electronics.

[13]  Mei-Ling Yeh,et al.  A High Efficiency Dual-Mode Buck Converter IC For Portable Applications , 2008, IEEE Transactions on Power Electronics.

[14]  Zhaoan Wang,et al.  Improving Light and Intermediate Load Efficiencies of Buck Converters With Planar Nonlinear Inductors and Variable On Time Control , 2012, IEEE Transactions on Power Electronics.

[15]  Milan M. Jovanovic,et al.  Light-Load Efficiency Optimization Method , 2009, 2009 Twenty-Fourth Annual IEEE Applied Power Electronics Conference and Exposition.

[16]  Wei Yan,et al.  A Noise-Shaped Buck DC–DC Converter With Improved Light-Load Efficiency and Fast Transient Response , 2011, IEEE Transactions on Power Electronics.

[17]  Ke-Horng Chen,et al.  Dithering Skip Modulation, Width and Dead Time Controllers in Highly Efficient DC-DC Converters for System-On-Chip Applications , 2007, IEEE Journal of Solid-State Circuits.

[18]  Jiin-Chuan Wu,et al.  A Monolithic Current-Mode Buck Converter With Advanced Control and Protection Circuits , 2007, IEEE Transactions on Power Electronics.

[19]  P.K.T. Mok,et al.  A 1-V integrated current-mode boost converter in standard 3.3/5-V CMOS technologies , 2005, IEEE Journal of Solid-State Circuits.

[20]  Tsz Yin Man,et al.  An Auto-Selectable-Frequency Pulse-Width Modulator for Buck Converters with Improved Light-Load Efficiency , 2008, 2008 IEEE International Solid-State Circuits Conference - Digest of Technical Papers.

[21]  G. Rincón-Mora,et al.  A comprehensive power analysis and a highly efficient, mode-hopping DC-DC converter , 2002, Proceedings. IEEE Asia-Pacific Conference on ASIC,.

[22]  Fred C. Lee,et al.  Improved light-load efficiency for synchronous rectifier voltage regulator module , 2000 .

[23]  T.H. Lee,et al.  A constant-frequency method for improving light-load efficiency in synchronous buck converters , 2005, IEEE Power Electronics Letters.