evaluation of transformer design

[[email protected]]

Hi, I have sent a post a while ago regarding a planar transformer
design. I have followed the guide given by Ferroxcube and came up with
the following calculations. It seems to me that my primary turns is
way to little.

Will anyone please comment on this and evaluate my calculations?

Results of core calculations

E-E14/E-PLT14 3F3 material
Ve (mm2) 300/240
Ae (mm3) 14.5
Maximum core Loss Density (mw/cm3) 1095/1225
Maximum Allowed Flux Density (T) 0.16
Primary Turns 2.182

E-E18/E-PLT18 3F3 material
Ve (mm2) 960/800
Ae (mm3) 39.5
Maximum core Loss Density (mw/cm3) 612/670
Maximum Allowed Flux Density (T) 0.125
Primary Turns 1.005

E-E14/E-PLT14 3C94 material
Ve (mm2) 300/240
Ae (mm3) 14.5
Maximum core Loss Density (mw/cm3) 1095/1225
Maximum Allowed Flux Density (T) 0.188
Primary Turns 1.864

E-E18/E-PLT18 3C94 material
Ve (mm2) 960/800
Ae (mm3) 39.5
Maximum core Loss Density (mw/cm3) 612/670
Maximum Allowed Flux Density (T) 0.151
Primary Turns 0.844


The specifications of the transformer were as follows:

a 1:1 transformer -

a planar type transformer - made on mulitlayer PCB

12A rms continous current in both primary and secondary.

resistance of winding must be as low as possible - less than 3-4
milliohms

frequency can be anywhere between 150-400kHz.

input/ output voltage is 8V peak to peak square wave - i.e. +-4V

as small as possible

core loss should be 100-400mW



Thank you

Johan Wagener