WEBENCH® Tools/LM3481: maximum flux density

zahra sq

Part Number: LM3481

Tool/software: WEBENCH® Design Tools

I designed two flyback converter with LM3481 with different specification, in both designs same core has been used (core material:N49, Core type:RM5).

in one of them Bmax=0.18T and another one Bmax=0.25T. why it choose these value for Bmax?

I want to know how we can determine Bmax in our design?

over 6 years ago

0 Youhao Xi over 6 years ago

TI__Guru* 78070 points

Hi Zahra,

The Webench references to a library of parts from third vendors. Magnetics vendors usually produce a family of series flyback transformers with the same core, but the turns ratio is changed to fit for different input/output applications. In your examples, it seems to be the same family but the primary turns are different, resulting different Bmax.

In a design, the rule is, keep Bmax below Bsat, or the transformer will saturate and cause damage. For N49, I would not recommend Bmax>0.3T.

Thanks,
Youhao Xi, Applications Engineering

0 zahra sq over 6 years ago in reply to Youhao Xi

Prodigy 190 points

Hi Youhao,

thanks for your help

How can we choose the best value for ΔB to determine primary turn?

0 Youhao Xi over 6 years ago in reply to zahra sq

TI__Guru* 78070 points

Hi Zahra,

I recommend you to read the following article to get a better understanding of the magnetics design.

www.ti.com/.../slup127.pdf

Thanks,
Youhao

0 zahra sq over 6 years ago in reply to Youhao Xi

Prodigy 190 points

Hi Youhao,

thanks for your help.

Regards,

Zahra

Power management

Power management forum

WEBENCH® Tools/LM3481: maximum flux density