An apparatus comprising: a switched-capacitor converter including multiple capacitors (Cres1, Cres2), wherein the multiple capacitors comprise a first capacitor (Cres1) and a second capacitor (Cres2); a transformer including a primary winding, wherein the apparatus is operative such that the multiple capacitors (Cres1, Cres2) are controllably switched in a circuit path including the primary winding to convert a first voltage into a second voltage; and a voltage converter coupled to a secondary winding of the transformer, wherein the voltage converter is operative to convert the second voltage into an output voltage; a controller operative to switch the switched-capacitor converter between a first resonant frequency mode and a second resonant frequency mode, characterized in that i) the first resonant frequency mode is operative to charge the first capacitor (Cres1) via an input voltage and discharge the second capacitor (Cres2) through the primary winding, and ii) the second resonant frequency mode is operative to charge the second capacitor (Cres2) via the input voltage and discharge the first capacitor (Cres1) through the primary winding, wherein operation in the first resonant frequency mode includes activation of first switches (Q1, Q3) in the switched-capacitor converter, wherein the activation of the first switches (Q1, Q3) allows for current to flow from the first capacitor (Cres1) to the primary winding of the transformer by a series connection comprising the first switches (Q1, Q3) and the primary winding, and wherein operation in the second resonant frequency mode includes activation of second switches (Q4, Q6) in the switched-capacitor converter, wherein the activation of the second switches (Q4, Q6) allows for current to flow from the second capacitor (Cres2) to the primary winding of the transformer by a series connection comprising the second switches (Q4, Q6) and the primary winding. a switched-capacitor converter including multiple capacitors (Cres1, Cres2), wherein the multiple capacitors comprise a first capacitor (Cres1) and a second capacitor (Cres2); a transformer including a primary winding, wherein the apparatus is operative such that the multiple capacitors (Cres1, Cres2) are controllably switched in a circuit path including the primary winding to convert a first voltage into a second voltage; and a voltage converter coupled to a secondary winding of the transformer, wherein the voltage converter is operative to convert the second voltage into an output voltage; a controller operative to switch the switched-capacitor converter between a first resonant frequency mode and a second resonant frequency mode, characterized in that i) the first resonant frequency mode is operative to charge the first capacitor (Cres1) via an input voltage and discharge the second capacitor (Cres2) through the primary winding, and ii) the second resonant frequency mode is operative to charge the second capacitor (Cres2) via the input voltage and discharge the first capacitor (Cres1) through the primary winding, wherein operation in the first resonant frequency mode includes activation of first switches (Q1, Q3) in the switched-capacitor converter, wherein the activation of the first switches (Q1, Q3) allows for current to flow from the first capacitor (Cres1) to the primary winding of the transformer by a series connection comprising the first switches (Q1, Q3) and the primary winding, and wherein operation in the second resonant frequency mode includes activation of second switches (Q4, Q6) in the switched-capacitor converter, wherein the activation of the second switches (Q4, Q6) allows for current to flow from the second capacitor (Cres2) to the primary winding of the transformer by a series connection comprising the second switches (Q4, Q6) and the primary winding.