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Planar transformer design software

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Advanced Member level 5
Jun 13, 2021
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My Eagle Layout cant do the rounded turns for a planar design.
Is their any (preferably free) software which enables you to design a planar transformer windings PCBs?
I found lots of sites that have let me fill in a quote, but none offer you the software.....i hope it would tell the interwinding capacitance and likely leakage inductance too?

Must admit planar seems more arenet allowed multipel layers for the same coil, you seem to have to interleave with the other coil......and also, you cant really have anything but low number of your wanted duty cycle (at max power, nom vin) will be awkward to get, as you can only really have low numbers of turns.


EAGLE may be controlled by an external script. So you are able to design almost any shape you can imagine.
You may use any programming language to generate an EAGLE compatible script.
In the past I even used EXCEL to generate such EAGLE scripts.

Thanks, ...As such i am wondering about this kind of planar winding design as attached.....would i be right in saying this would be a very substantial EAGLE script?

I must confess i interviewed at a planar windings company called Himag some years ago....i spent some time with their Planar transformer designer, who was using their own proprietary software to do designs for really was quite a complex software program. It delivered the full lowdown on leakage L, interwinding C, etc well as full analysis of proximity and Skin losses etc etc.

I have searched around and cannot find anything like this as a free download. I am of the impression that if you want a planar transformer, you literally have to book a Teams meeting with a consultant and provide your spec...they then deem what is best for you...and for what i can only guess is a very considerable payment, they then design it for you.......if you want it slightly modified, then presumably you have to go right through all of this again?


  • Planar windings.jpg
    Planar windings.jpg
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From your previous post I guess you don't want 16+ layers, nor extremeky high frequency, no high accuracy...
And this post is rather vague on informations about your true application.

So why don't you tell us your requirements:
Layer count, material, core, current, inductivity.... or whatever you need

To be honest, we dont know yet, we are at the bidding stage, but just know its a SMPS with a planar on it , (approx 30vin 30vout, 400 = pout) and for whatever reason, it doesnt work properly. So the planar may have to be re-done. But from my research so far, it is not actually possible or adviseable for a person to design a planar unless they have the proprietary planar design software, which advises on things like need for interleaving, pairing for dv/dt, edge effect avoidance etc etc, best way to do lead frames, how to calculate stray C and L?

So my question, due to my research, is it actually even possible for an engineer to design a planar themselves without the highly expensive proprietary planar design software?

Thanks, the thing is also that planars need multiple interleave winding...which results in v v low leakage L.
This lowness of leakage inductance is not wanted in gard switched converters....its too low. Hard switched converters benefit from a certain amount of leakage inductance, as the attached sim shows (if you run it with v low L(leak) and then more L(leak). With very low leakage L, the current spikes are very high.


  • 2TFC
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