Simplified transformer design for a switching power supply

摘要

The invention is a transformer having one winding, for example the secondary, built as tracings in a first multilayer PC board. The primary windings are made as a separate second PC board. In an exemplary embodiment of the invention, the second PC board containing the primary windings is attached to the first PC board by attachment tabs built into the second PC board, and the tabs are soldered to receiving attachment pads of the first PC board. In another exemplary embodiment of the invention, the first PC board has various other components mounted thereon. For example, the secondary windings of a power transformer along with the power supply circuits are all built into a first single PC board. In another exemplary embodiment of the invention, the windings are etched as traces in copper layers of the PC boards as spirals. The spiral of one copper layer is connected to the spiral of a different copper layer by a via, or vias, formed through the insulating layer of the PC board. The vias are drilled, cleaned, and plated, with conducting material, for example copper. By using multiple layers, and by connecting spiral windings of each layer to the windings of the next layer by use of vias, any number of turns can be built into a primary winding, or into a secondary winding.