Methods to improve performances of the self-driven synchronous rectification technique

This paper presents two very simple methods or techniques which improve very efficiently two important hitches when self-driven synchronous rectification techniques are used in DC/DC power conversion. On the one hand, the output short-circuit condition becomes a problem due to the vertical rectification branch MOSFETs not being correctly driven; then, the short-circuit current circulates through the inherent diode or any additional diode. On the other hand, for the typical input and output voltages in telecommunication applications to date, the use of 200 V components in the primary side is necessary due to several constraints which avoid the usage of 100 V devices. This indeed is not a problem, however, if it were possible, some additional advantages could be achieved. After having explained these two problems, possible solutions found, how they work and the results that can be obtained with them are detailed. In conclusion, the authors have achieved a considerable improvement in the overall performance of the power converter. Several points of increase in efficiency and a very attractive cost reduction can be achieved with the usage of these two techniques.