An integrated inductor comprising a multi-winding inductor having a transformer winding and a resonant inductor winding, both windings (L1, L2) wound around a magnetic core comprising core pieces that form a central column which is surrounded by a closed magnetic circuit of connected magnetic elements of columns (12, 13) and yokes (21, 22) to which C-shaped (14, 15) and/ or E-shaped (16, 17) magnetic elements are connected, wherein the core pieces form a closed magnetic circuit, and wherein: - the resonant inductor winding comprises at least two resonant inductor winding parts (L2A, L2B), - wherein the multi-winding inductor is configured such that, when in use, currents flow simultaneously through the transformer winding and the resonant inductor winding, the magnetic induction in the magnetic circuit of the transformer winding overlaps with the magnetic induction in the magnetic circuit of the resonant inductor winding parts (L2A, L2B) in an area of common parts, of the magnetic core, - wherein the transformer winding of the multi-winding inductor is wound around the central column of the magnetic core, - wherein a first air gap is formed in the central column or a pair of first air gaps is formed at the ends of the central column; - and wherein the resonant inductor winding parts (L2A, L2B; L2C, L2D) are would around the C-shaped (14, 15) and/or E-shaped (16, 17) magnetic elements of the magnetic core, - wherein second air gaps are formed between the closed magnetic circuit of magnetic elements (12, 13, 21, 22) and the C-shaped (14, 15) and/or E-shaped (16, 17) magnetic elements; - and wherein the first air gap or the pair of the first air gaps have a width adapted so that the magnetic induction produced by the resonant inductor winding does not exceed 25% of the magnetic induction produced by the transformer winding in the central column while currents flow simultaneously through both the transformer winding and the resonant inductor winding. - the resonant inductor winding comprises at least two resonant inductor winding parts (L2A, L2B), - wherein the multi-winding inductor is configured such that, when in use, currents flow simultaneously through the transformer winding and the resonant inductor winding, the magnetic induction in the magnetic circuit of the transformer winding overlaps with the magnetic induction in the magnetic circuit of the resonant inductor winding parts (L2A, L2B) in an area of common parts, of the magnetic core, - wherein the transformer winding of the multi-winding inductor is wound around the central column of the magnetic core, - wherein a first air gap is formed in the central column or a pair of first air gaps is formed at the ends of the central column; - and wherein the resonant inductor winding parts (L2A, L2B; L2C, L2D) are would around the C-shaped (14, 15) and/or E-shaped (16, 17) magnetic elements of the magnetic core, - wherein second air gaps are formed between the closed magnetic circuit of magnetic elements (12, 13, 21, 22) and the C-shaped (14, 15) and/or E-shaped (16, 17) magnetic elements; - and wherein the first air gap or the pair of the first air gaps have a width adapted so that the magnetic induction produced by the resonant inductor winding does not exceed 25% of the magnetic induction produced by the transformer winding in the central column while currents flow simultaneously through both the transformer winding and the resonant inductor winding.