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UCC3808A-1: High magnetizing current in Push Pull topology and effects in current measurement

Part Number: UCC3808A-1

Hello everyone,

I am desiging with a Push pull topology a 500W DC-DC converter (Vin=24V +- 10%, Vout=200 V at 100 kHz). The current mode controller IC tha I am using is the UCC3808A-1.

The design (I followed Mclyman procedure) gave me that I can use a relationship n=Np/Ns=1/12 with a EPCOS-TDK E core 55/28/21 ( that has an AL=6400nH, where:

Imag=Vin_min*D_max / (L_mag*f_sw=26.04A,



If you are noticing, the magnetization current is higher than the input current. I am going to measure the current with a current transformer, but I have the following questions (I am going to give them a number so that it can be easier to answer them):

1) Is it ok that Imag>Iin? What do you guys think about it?

2) The controller could be affected somehow by that magnetizing current? if yes, what do you suggest me to solve it.

3) The current transformer could be affected somehow by the magnetizing current? if yes, what do you suggest me to solve it.

Thank you for your help. Have a nice day.