Electronic – Flyback SMPS Transformer choice

flybacknxpswitch-mode-power-supply

In several projects so far, I have been using old "fashioned" transformer based power supplies. However, this time around I want to use a switching mode power supply. The supply will be used to power some 5V micro controller and supporting electronics. The power requirements are equivelent to that of a old usb phone charger (which for several reasons is not going to be used.)

After some research on the internet I found a very neat tool by NXP, which helps with most of the complicated mathematics involved:
http://nxp.transim.com/fb/design.aspx
So far i have been using the default specifications (universal mains, 5V, 5W, integrated FET, TEA1721)

Unfortunately i get stuck at the part where i have to choose the transformer (the bottom 3 choices from the "design" tab).

For instance, i want to use the following transformer:
http://nl.farnell.com/bi-technologies-tt-electronics/hm42-10001lftr/transformer-gate-drive-300uh/dp/2192063
The tool proceeds to ask questions such as: Winding ratio, primary inductance and last asks the specific transformer you use.

The datasheet of the transformer(sorry, cant post more than 2 links) i was planning to use (and also several other transformers out there) do not answer there questions. Because of this I get the feeling that when designing a SMPS also a specific transformer is designed.

So the above boils down to: where can I find the data required to completely fill out the design tool?

Any help is much appreciated, thanks in advance!

Kind Regards,
Victor

Best Answer

For instance, i want to use the following transformer: http://nl.farnell.com/bi-technologies-tt-electronics/hm42-10001lftr/transformer-gate-drive-300uh/dp/2192063

You can't use the transformer you want to - it isn't rated for doing what you want.

Unfortunately i get stuck at the part where i have to choose the transformer (the bottom 3 choices from the "design" tab).

What's wrong with the design page that it produced: -

enter image description here

It tells you: -

  1. The core (E16/8/5, Ferroxcube, 3C90, 570µm)
  2. The gapping (0.57 mm)
  3. How many turns for primary, auxiliary and secondary
  4. How to wind them
  5. The wire gauges

It even gives you options for using different ferrite cores - see radio buttons.

What were you expecting? You want something easier? Yes, well go to premier magnetics and choose a design for 5V and 1A (such as this one) and they do the job for you using a Power Integrations part: -

enter image description here

They'll sell you the transformer and provide all the info for the other magnetics. If you are still insistent on using the NXP tool then start learning about transformers so you can take the premier magnetics transformer and feed the data back into the tool.