Planar transformer having integrated ring core

A planar, intrinsically safe transformer having a vertical dimension and a horizontal dimension, comprising:

• a sandwich-type layer structure including a plurality of layers extending horizontally and arranged vertically on top of one another, comprising a first and a second conductive layer and at least one insulating inner layer disposed between the two conductive layers;
• a plurality of electrical circuits, wherein a first electrical circuit and at least a second electrical circuit are galvanically isolated from each other;
• and
• at least one ring-type magnetic core having a hole, which acts at least on the first electrical circuit and on the second electrical circuit, wherein the core is arranged within the at least one insulating inner layer;
• a conductor of the first electrical circuit and a conductor of the second electrical circuit each have a winding with at least one winding turn, wherein the at least one winding turn of the first electrical circuit and the at least one winding turn of the second electrical circuit each extends along the first conductive layer and along the second conductive layer and through the at least one insulating inner layer and through the hole of the core;
• and
• an insulation provided around the magnetic core enclosing the magnetic core in all spatial directions, wherein the insulation is formed by the insulating inner layer and has a thickness, which guarantees a second isolation distance between the core and all other electrically conductive structures of the electric circuits and which is equal to or greater than half a first minimum isolation distance, wherein the first minimum isolation distance is defined as a minimum separation distance between the first electrical circuit and the second electrical circuit.