Synchronous Rectifi cation (SR) is mandatory to achieve good effi ciencies with low output voltages. If the transformer is driven asymmetrically without dead times, Self-Driven Synchronous Rectifi cation (SDSR) is a very interesting solution. However, if the transformer is driven symmetrically, the synchronous rectifi ers are off during the dead times and, as a consequence, the effi ciency is lowered. This paper deals with the optimisation of a SDSR system that keeps the rectifi ers on even during the dead times. The system is based on using the output inductor to turn the SR on and the power transformer waveform to turn them off. Hence, the most important parameters have been studied in order to obtain the highest possible effi ciency. This system is very interesting because it can be used in any topology with a symmetrically driven transformer independently of the output voltage level and for a wide input voltage range. The system has been implemented in a prototype in order to measure the real effi ciency that can be achieved with the proposed scheme and compared with the effi ciency of the same prototype without SDSR.