Heat sink for buck converter

[dko]

I have to start with saying that power electronics is something totally new for me so it's possible my question is quite stupid.

I would need to design a heat sink for a buck converter. I have to take the diode and the active switch into account. But how do I do the calculations? The diode is off when the switch is on and v.v. Does this mean I just have do the calculations for both components separately and design the heat sink for the one with highest temperature, or do I have to make some kind of total calculation? In this case, how do I it?

Thanks beforehand!

 

[marthinus]

The loss of the switch over one cycle plus the loss of the diode over one cycle gives you the total loss over the cycle. Multiply that with frequency to give you the total heat energy per second into the heatsink.

 

[dko]

Thanks a lot for your answer!