A voltage-mode hysteretic boost DC-DC converter with dual control modes

The conventional voltage-mode hysteretic buck converters have the merit of fast response and yet stable operation. However, such merits cannot be extended to its counterpart boost converters. This is so simply because the waveforms of the input current and output voltage of buck version are in-phase, but they are out-of-phase in the boost version. This led to the development of several excellent hysteretic boost converters only in current-mode. Due to the design simplicity of voltage-mode, this study presents a voltage-mode hysteretic buck converter design, where two control modes are employed. During the start-up period, the pulse with a constant duty is applied to control the power switches, the hysteretic control takes place when the output voltage reaches to the desired level. The proposed converters achieve fast transient response and good conversion efficiency.