Design and analysis of a coreless flyback converter with a planar printed-circuit-board transformer

In this paper the development of a 1W DC/DC converter is presented. It is based on a flyback converter for simple applications. The transformer is designed in a form as a spiral coil on a PCB. The special feature of the converter is that the flyback converter is laid out without a core. The area (diameter) of a spiral coil should be bigger as a coil with a core because the air is not a good energy store. The advantage of a coreless transformer is the PCB-Design. The paper describes the theory of the flyback converter and shows a way of the implementation of the coreless planar transformer. An analysis shows some results by different geometry and frequency of the planar transformer.