They all look like the letter ‘E’, but the center part is different for each substance. However, E cores have several cases, such as EE, EI, EFD, ER, etc. The E cores are the most popular and are widely used in SMPS transformers. Here the term, TIW stands for Triple insulated wire construction. This table will be useful to select the right core for your transformer design based on its wattage rating.įerrite cores for Margin Wound construction The source of the list is taken from Power Integration documentation. The list is based on 0-100W construction. Here is the list of cores depending on the wattage. However, Cores have a direct relationship of the output wattage, thus for different wattage of SMPS different shape and size of cores are required. The above image is a datasheet of EE25 core of PC47 material from a widely popular core manufacturer TDK. Each and every bit of information will be needed for transformer construction. Also, the manufacturer of ferrite cores provides detailed parameters in the datasheet, which will be useful while selecting the core for your transformerįor instance, here is a datasheet of popular core EE25. Popular type of core material are N67, N87, N27, N26, PC47, PC95, etc. A core has a different type of A L (Ungapped core inductance Coefficient) depending on the core material, core size, and core type. The transformer core design is the most important thing in an SMPS transformer construction. High switching frequency opens up the possibilities to choose smaller SMPS transformers these high frequency, SMPS transformers uses ferrite cores. The properties of an SMPS transformer are highly dependent on the frequency in which they operate. SMPS stands for switch-mode power supply unit.

These parts hold same in most cases for other types of transformers as well. The parts present in a transformer are explained below, we will learn the importance of each part and how it should be selected for your transformer design. If you are completely new to transformer then please read the Basics of Transformer article to better understand the proceedings.Īn SMPS transformer design has different transformer parts which are directly responsible for the performance of the transformer. Do note that this tutorial covers only the theory using which later in another tutorial we will build a 5V 2A SMPS circuit with a handmade transformer as shown in image above for practical exposure. So in this transformer design tutorial we will learn how to build our own transformer as required by our circuit design.

Most times these transformers are not available off the shelf in the exact same parameter that suits our design. Those who have already worked with SMPS circuits would easily agree that the flyback transformer design plays a vital role in designing an efficient power supply circuit. Designing an efficient Power Supply circuit is not less of a challenge.

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