说明：  Embedded applications have emerged appreciably during the past few years due to the considerable increase of nomad and traveller ways of life. These itinerant lifestyles induce the apparition and development of more and more portable and autonomous systems. As a consequence, energy sources, their corresponding storage devices and power management control systems should be improved substantially to obtain an optimal and long-lasting working operation. Consequently, new issues in the quest for longer power autonomy have appeared recently. Furthermore, embedded products own strict power supplies design requirements which are becoming more and more critical with the increasing complexity of the functionalities proposed by these new portable devices