I have a 415V,50Hz SMPS using TOP264. I am facing heating issues with the SMPS. I have used a MOSFET in series with the internal MOS of the Top264. The Mosfet and the IC have severe heating problems. I have attached an image showing the part of the circuit having issues. It also shows the voltages at several points in that path. Can anyone point out some factors which may be causing this problem?