Hi All,
Please teach me how to calculate and select heat sink for mosfet used in flyback converter .
Please guide me with a good example or application note.

 

hi 2293,
These two heat sink PDF's may help.
E

 

That`s very simple, if the accuracy is not demanded below the some 20 or 30%. Apply the natural convection 1square inch of ribbs is 1W.
If forced cooler, then each pentium4 square type cooler with original fan about 100, or max max 150W; pentium 5 the same about 200-300W (last those with copper round core in aluminium.
If need to know more precise, the experiment will give faaaaaar more exact result as the best modelling softs or formulas. Just put on the box-type screwable resistor with some 20-50W, switch it on lab power source and wait some 10 minutes, then measure the temperature. Thus the Watts per Centigrade will be clarified.