New post-regulation and protection methods for multiple output power converters with synchronous rectification

The evolution of microelectronics to very low voltage supplies (3.3 V, 2.7 V, 1.5 V...) introduces a new challenge for telecommunication equipment: DC/DC power converters have to keep very high efficiencies and nowadays this is not possible by using classical rectifier diodes. This is one of the key reasons to justify the increasing use of synchronous rectification in DC/DC power converters for telecommunication applications. This paper presents two techniques (one to post-regulate the nonregulated outputs in multioutput converters and the other to achieve an easy and cheap over or under voltage protection) taking advantages of the rectifier MOSFETs used in synchronous rectification. A multioutput power converter using these techniques and with windings integrated in the PCB was built and the results are presented.