short circuit protection is not working

Hello,

Please help, I have tried with different design of transformer, but still 

getting same problem.

Please help

please share with us your system schematic and PIXL design. Also, what is the short circuit test IC you refer to?

I have added additional current limit circuit, as shown in schematic. Does inductance of transformer

has any effect on short circuit protection?

I assume you blow up TOP IC or your external short circuit protection IC?

one possibility is that your transformer is saturated under higher bus voltage and current increases dramatically during on time. You can probe the primary current with graduatlly increased Vac.

Yes sir, TOP IC blows up. I have tried different inductance values of primary winding to avoide transformer

saturation. I have also tried various turns ratios including the one which is given by PI Expert. I have also 

tried removing external short circuit components. Still same happens. Please find attached PCB layout.

did you share with the PIXL file, that will help us to understand the design.  

Sir,

Please check the attached PIXL file.

when I open your PIXL file, it is not readable. maybe you can convert it into PDF?

Please capture the primary waveform with lower Vac where you mentioned is not blow up, and around the boundary where blow up start to happen. Also monitor the wavefrom at the blow up event. That helps to dignose.