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     regarding transformer construction, we find some differences in the specifications given by PIXL DESIGNER SHEET and DESIGN EVALUTION REPORT. For example rdr193 uses RM6 CORE with 128 turns primary with 35awg copper. But if you put the same driver spec in the PIXL design software,   the output sheet gives 119 turns  primary with 34awg copper for the same RM6 core. I am attaching the pixl design sheet for the same spec of rdr193 herewith. It shows differences for secondary and bias winding also. Please explain the difference.  What is the procedure for designing correct transformer?\



LinkSwitch-PH 7w Design1.xls52 KB

If you input exactly the parameters shown in RD193, you will end up with the same (or atleast closer) transformer design.

I would like to mention some parameters that are not similar between the two spreadsheet: Current Limit Mode, IFB, KP, VOR, NS. The difference on these values explains why you are getting unidentical results. 


If you are working on a very similar design, then I advise that you follow the design of RD193. Basically, the PIXLS Designer gives you the flexibility to tweak your design for various reasons such as when you need to use a different core size, if you want to further improve efficiency, or if you want to use different components such as output diode.


I found AN49 to be a good article that you can read in order to help you understand better about the  step-by-step design procedure.