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LM5155: Webench Flyback Useless w/ Standard Transformers?

Aaron
Prodigy 60 points
Part Number: LM5155

Tool/software:

Hello,

I would like to use the Webench to design an isolated flyback converter with the LM5155. However, when attempting to select an off the shelf transformer, the calculations die. My application uses the internal bias supply, and does not require an aux winding or custom magnetics. Therefore, unless I'm missing something, the Webench for LM5155 flybacks is mostly useless unless you want to use exactly the custom windings initially prescribed by the designer?

How hard would it be to get a variant of Webench that works with the internal LDO?

Or is there some way to manually adjust the three winding "custom" transformer to mimic the performance of a standard transformer with bias supply?

Thanks

  • 0
    TI__Genius 16235 points

    Hi Aaron, 

    Thanks for reaching out. For the Webench related question i will assign this thread to the Webench team. 

    To design the isolated flyback with LM5155, i can also recommend to use our quickstart calculator for this device: https://www.ti.com/tool/download/SNVC240 

    Best regards

    Moritz

  • 0
    TI__Expert 3140 points

    Hi Aaron,

    Thanks for above post. However for us to get the variant of WEBENCH model with internal LDO, we will need to get the request from respective BU. Any modification to WEBENCH model needs to be approved by product experts. However, if you need any support wrt device application circuit, our product experts can help, kindly let us know.

    Best regards

    Shaheen

  • 0 in reply to Shaheen Makandar
    Prodigy 60 points

    I understand that you have a chain of authority to respect, but please do make this request of the LM5155 product owners. The tool would be orders of magnitude more useful to everyone with *any* added flexibility on the transformer. With a two winding design, even users who are custom winding transformers with aux windings could still use the tool. As it is, they are the ONLY customers who can use the tool.

    At the moment, I'm attempting to use it to tune my compensation network, for which the spreadsheet is of little help. This is not really the kind of thing it would be convenient to work out here at all. As I'm sure you can understand.

    Please let me know when you submit or discuss this with product experts. I will eagerly await your update.

  • 0 in reply to Aaron
    TI__Expert 3140 points

    Hi Aaron,

    Sure, we understand your point . We will check this with product experts and get back to you with the update as soon as we get a response. 

    Best regards,

    Shaheen

  • 0 in reply to Shaheen Makandar
    TI__Expert 3140 points

    Hi Aaron,

    We are working on adding standard  transformer support for the device on WEBENCH, once done we will provide you the update. Tentatively by next WEBENCH release(month end).

    Best Regards

    Shaheen