A Zero Current Detector with Low Reverse Current by Forcing Freewheel Switch Operation in Buck Converter
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At light load condition, buck converter usually requires a zero-current detector (ZCD) to prevent reverse current flowing back to the source to improve conversion efficiency. This paper presents a ZCD with enhanced time response of the freewheel switch operation. The proposed ZCD was simulated using a 0.18-µm CMOS process in a PWM voltage mode control type-III compensation buck converter, to convert a DC input voltage of 3.3V to a DC output voltage of 1.8V. The buck converter was designed to work in CCM at heavy load, PFM at light load, and DCM in a short transient between CCM and PFM. The PWM switching frequency is 2MHz, and the output load current range is from 20mA up to 300mA. The proposed ZCD was tested as compared to the conventional one for the same condition, showing maximum improvement of 6.9% in efficiency in PFM, making the overall conversion efficiency greater than 89.7%.
Abstract
At light load condition, buck converter usually requires a zero-current detector (ZCD) to prevent reverse current flowing back to the source to improve conversion efficiency. This paper presents a ZCD with enhanced time response of the freewheel switch operation. The proposed ZCD was simulated using a 0.18-µm CMOS process in a PWM voltage mode control type-III compensation buck converter, to convert a DC input voltage of 3.3V to a DC output voltage of 1.8V. The buck converter was designed to work in CCM at heavy load, PFM at light load, and DCM in a short transient between CCM and PFM. The PWM switching frequency is 2MHz, and the output load current range is from 20mA up to 300mA. The proposed ZCD was tested as compared to the conventional one for the same condition, showing maximum improvement of 6.9% in efficiency in PFM, making the overall conversion efficiency greater than 89.7%.
참고문헌 (12)
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