Low Voltage High Efficient Synchronous Buck Converter for Mobile Chargers

Abstract

— The problems faced in a typical buck converter is the high output ripple and slow transient
response, which is not suitable for present-day portable systems. The semiconducter industry has developed
low cost DC/DC converters that employ synchronous rectification that are more efficient than nonsynchronous
DC/DC converters. The switching loss in the converter circuit causes reduction in efficiency. In
order to increase the efficiency and to reduce the electrical noise in output, soft switching topology is
introduced in the synchronous buck converter. A zero-voltage-transition (ZVT) synchronous buck converter
is hereby presented, which is capable of providing appropriate low voltage & high efficiency needed for
electronic devices. In order to eliminate the switching losses, an additional passive auxiliary circuit is
included in the ordinary sychronous buck converter which permits the main switch to work with zerovoltage
switching. The additional circuit gives higher efficiency due to the soft switching conditions in the
main switch and other semi-conducter devices. The viability of the auxiliary circuit is accordingly
authenticated by simulation and experimental findings.
Keywords--- Zero Voltage Transition, Zero Current