as seen in fig4 and 5 fig4 shows variation of vout y axis versus load current x axis for switching frequencies of 250 hz 500 hz 1 mhz 1 5 mhz and 2 mhz fig5 shows efficiency y axis versus load current x axis for the same switching frequencies re is reflected by the vout drop and directly correlates to the efficiency when the load exceeds 2 a so when the ohmic losses dominate also we note that this optimum also depends on the load it is 300 khz at 10 a and u02dc 500 khz at 5 a then 300 khz at 2 a if other parameters cf cr vary this optimum changes again this frequency optimum would not only require the knowledge of cf cr but also would vary with iload also cf and cr have nominal spread and are de rated and this de rated value can vary with the time if vin and vout vary cf and cr vary too furthermore rdson also varies with vin and with the die temperature thus making the optimum value of rdson variable too this calls for 4 dimension look up tables to adapt the frequency to these parameters to be able to maintain the optimal efficiency otherwise in case the choice relies on one frequency then between 1 and 3 of efficiency is lost around 95 of this depending on the load in ccm which corresponds to 20 to 50 more losses and more self heating the disclosure provides for maximum efficiency point tracking mept of charge pump operation it is very cheap and in a preferred embodiment tunes the frequency of.