Abstract: The structure of the power transformer has a great influence on the safety structure of the power adapter product, so the power adapter must be clear about the structure of the power transformer in the design and production, and carry out a reasonable component layout and structure design of the product, so as to avoid the adverse impact of the power transformer structure. Taking the power adapter (including travel charger) and the power transformer commonly used in the extension cord socket with USB adapter as examples, this paper analyzes the structure and requirements of different power transformers, and the influence of power transformer structure on the product safety structure of power adapter (or including adapter module).

Key words: Primary winding, Secondary winding, Magnetic core, Creepage distance, Electrical clearance