Primary inductance & gap length of flyback transformer

Thread Starter


Joined Mar 16, 2010
Hi all,

I am working on a CCM flyback transformer with multiple outputs, precisely 2. 1 for the high output device i will use and another to power the this book, there is only 1 output. (page 54)

1.How do I calculate the Im & Lm?Considering the Im is based upon the ratio of n2/n1 since I will have n3,my 3rd output? (page 56)
2.And also, how do I calculate the Lg gap length? (page58)

I will appreciate if someone can give me the formulas for the above mentioned.

Thank you.


Joined Sep 9, 2010
You haven't said what the load draws are, but perhaps a simplifying approach might be to ignore the relatively smaller current needed to power the IC?

I suggest drawing a schematic of your particular design. You'll get better help here if folks can SEE what you're talking about.