Tool selects discontinuous mode flyback transformers

January 19, 2015 // By Graham Prophet
For discontinuous mode, flyback, SMPS designs, an online tool has been launched by Wurth Electronics Midcom Inc. Entering as little information as input voltage range, switching frequency, output voltages and current, the Smart Transformer Selector, or STS, will return a list of prequalified, off-the-shelf transformers.

STS searches Wurth Eletronics Midcom’s database of hundreds of SMPS transformers designed for discontinuous mode, flyback operation. The STS uses power supply parameters and searches the database for parts that will not saturate, will provide the proper output voltages, will not over stress your switch, among other parameters. STS looks at each transformer and does a reverse design to make sure that it will function properly under the operating conditions that you specify.

The search results are returned in a table that lists many of the typical transformer parameters, such as inductance, turns ratio and saturation current along, with mechanical and safety parameters for the parts. Full specifications of the part are available for immediate download in pdf format right from the table. The STS finds all suitable transformers, even those that were not designed specifically with the given application in mind.

Selecting any part from the list will populate an analysis tab directly below the chart which summarises the part and its performance in the application. It shows everything from current wave forms, voltage levels and power losses to mechanical dimensions, a schematic for the application and a 3D image showing what the part looks like. To get more detailed information one of three tabs available reveals the details of the currents, voltages and losses.

Specifying duty cycle, MOSFET and diode rating, as well as the controller used, are all options that can be used by the advanced user. The STS will take all of these requirements into account when searching for a transformer. For all users, a limited list of controllers from the IC manufacturers is provided for selection. Specifying the controller will automatically populate the duty cycle, MOSFET parameters, and the UVLO-LO and UVLO-HI parameters as they pertain to the controller. Users can still override the auto settings if they wish as in the case of an external switch being chosen rather than using the one internal