Tool/software:
used webench for a flybench DC/DC circuit with the LM3481 ic controller. i took the suggested BOM and made the circuit into a prototype PCB . the circuit details are AC/DC 17v-42v input with a 24v DC output at 2.5A. The protype works (regulates 24V fine) under light loads but anything over 1.0A the out FET and transformer get redic hot(>90°c). So hot that the out FET destroyed itself. So after looking at the layout which was outsourced i realized they didnt follow proper thermal area for the FET for heatsinking. So before replacing the original FET just to have that happen again because of the obvious lack of heatsinking for the proper power dissipation i used an equivalent FET in a TO-220 package with a very large heatsink. However, that is still getting too hot(>80°c) with anything over 1.0A . the switching Freq was designed at 227K hz and i reduced it to 100K hz and that helped only by about 5-10°C. i am thinking of trying other FET's with a lower RDS on and less gate charge but what else could cause the Transformer and the FET to overheat?
