LM5030: Transformer topology constant formula

Aykut ULUSAN

Intellectual 365 points

Part Number: LM5030

Hello,

in LM5030 push-pull transformer design notes by Michele Sclocchi

Topology constant formula is given as below,

But topology constant in some sources is given as below

topology constant for push-pull : 0,001

topology constant for forward: 0,0005

so where does it come from (1 / 1.97) * 10^3 ?

And Shouldn't it be 0.001 instead of 0.0005?

thanks in advance

over 4 years ago

0 Hong Huang over 4 years ago

TI__Guru 73085 points

Hi,

It is better you contact Michele Sclocchi directly if you have questions on his article. At least please attach his article so we can read to see if there is clue why.

0 Aykut ULUSAN over 4 years ago in reply to Hong Huang

Intellectual 365 points

You're right, sorry, I couldn't add the document but i can give a link

http://educypedia.karadimov.info/library/LM5030_Push-Pull-12V-60W-2001i-new-4.pdf

Second document for topology constants

www.mag-inc.com/.../Transformer-Design-with-Magnetics-Ferrite-Cores

0 Hong Huang over 4 years ago in reply to Aykut ULUSAN

TI__Guru 73085 points

Hi,

As you mention, in some sources, Kt is different, please provide the "some sources".

I think (1 / 1.97) * 10^3 may be the author's own defined coefficient. As in this article, Kt has no definition, so it is difficult to judge.

0 Aykut ULUSAN over 4 years ago in reply to Hong Huang

Intellectual 365 points

Other source is ferrite core manufacturer, magnetics.

the author used the product of the same company but I didn't find formula relation

https://www.mag-inc.com/Design/Design-Guides/Transformer-Design-with-Magnetics-Ferrite-Cores

+1 Hong Huang over 4 years ago in reply to Aykut ULUSAN

TI__Guru 73085 points

Hi,

Since the author is not with TI anymore, I suggest you contact Magnetics on Kt. I would guess more likely, you should follow the Magnetics as one of the key reason is you are able to make contact them and also it is a magnetic company. One more reason is it looks to me the Kt in the NS author's article may have different definition. But since the author is not with TI anymore, it is difficult to find how he defined the Kt.

Power management

Power management forum

LM5030: Transformer topology constant formula