Integrated transformer

An integrated magnetic circuit for a resonant converter, comprising:

• a plurality of transformer cells arranged in a stack structure, the individual transformer cells including:
• a transformer core structure;
• a transformer primary winding formed as a conductive structure on or in a transformer cell printed circuit board (PCB) extending around one or more transformer cores in an infinity winding arrangement;
• a transformer secondary winding formed as a conductive structure on or in the transformer cell PCB extending around the one or more transformer cores in the infinity winding arrangement;
• and
• a secondary transistor or a diode mounted on the transformer cell PCB and coupled in series with the transformer secondary winding between a first converter output and a second converter output.

An LLC resonant converter, comprising:

• a switching circuit to provide an alternating voltage at a switching node;
• a capacitor, an inductor, and a plurality of transformer primary circuits coupled in a series circuit between the switching node and a reference node;
• a plurality of transformer cells arranged in a stack structure, the individual transformer cells including:
• a transformer core structure;
• a transformer primary winding extending around one or more transformer cores in an infinity winding arrangement;
• a transformer secondary winding extending around the one or more transformer cores in the infinity winding arrangement;
• and
• a secondary transistor or a diode coupled in series with the transformer secondary winding between a first converter output and a second converter output;
• and
• a control circuit including a first output to provide a primary side switching control signal to operate a switch of the switching circuit to provide the alternating voltage at the switching node.