on capacitor 32 whatever the measures adopted to detect a failure of power input supply 1 and to generate the data save request the save circuitry which for simplicity is assumed to be arranged within board 15 but in various embodiments can also be implemented in different ways according to criteria known in themselves is powered during data saving thanks to the energy stored in capacitor 3 with such an aim in order to transfer the energy stored on capacitor 3 towards the save circuitry both in the presence of storage capacitor 12 whose size can be reduced and in the absence of capacitor 12 it is possible to follow different methods for example as exemplified in fig6 in various embodiments it is possible to use auxiliary power stage 10 11 so that the energy of capacitor 3 is transferred from primary side 10 to secondary side 11 and therefrom towards the save circuitry in this case in various embodiments it is possible to switch off for example through lines 19 and 22 the main power stage avoiding the unnecessary absorption thereby of useful energy stored in capacitor 3 at this point in practice only the auxiliary power stage 10 and 11 will absorb energy from capacitor 3 and it will be possible to use that energy to power the save circuitry of the operational data of the converter in various embodiments this can virtually allow to dispense with storage capacitor 12 or at least to reduce its capacity value and therefore its size and cost to minimum values an auxiliary power stage with a flyback arrangement offers the possibility to use flyback capacitor 12 b in order to perform.