Output rectifying diode burning up in LED driver
Your Diode is burning up due to speed because your volts and amps are OK .Paralleling them wont do much here proving that it is not a peak current issue .The Flyback is cheap but does have high peak currents .If you experimentally place 2 diodes in series and you find that things are a little cooler then you are on the right track .Getting a fast diode with better reverse recovery times will help .The better diode will also make the switching device run cooler .When using cheap normal Si fast diodes the lower voltage types are faster .This observation can by justified by semiconductor physics .Do your homework and find what voltage you need for the output diode .It wont be anywhere near 600V .They make 200V shottkies .Increasing the gate resistor will cool the diode and warm up the Fet and help EMC .