The EFD15 is a Transformer Economic Flat Design (EFD) Core made with material grade of 3F3. It offers a significant advance in circuit miniaturization. Its low build height and high throughput power-density make it ideally suited to applications where space is at a premium. Throughput power of a ferrite core transformer is essentially proportional to its volume. So the transformer is one of the main limitations in a DC-DC converter size. Now, with the introduction of the EFD system, a significant reduction in transformer core height has been achieved. EFD transformer core combines both extreme flatness with a very high throughput power-density for frequencies up to 1MHz and higher. Every transformer, based on the EFD range, has a lower building height than any other existing low-profile design with the same magnetic volume. This is achieved by placing the centre pole of the core always in the centre of the finished transformer, thus making maximum use of the winding area.