Re: Heatsink for DPAK

I've done it. And the result during the switching time is

Ps = 1/2*(Rds_on*I^2)*fs*(tc_on+tc_off).

That result takes into account the integral that you mean, at least
that is what I've understood from a book. Wasn't it waht you meant ?

I still don't follow your equation. It looks from first glance to be
dimensionally incorrect.

Ignore the stead state dissipation, that's simple enough. How exactly
did you calculate the dissipation during the switching periods ?

Graham

It's not dimensionally incorrect :

- Rds_on * I^2 = Rds_on * I * I = Vds * I = Watt
- fs = 1/sec
- tc_on and tc_off = sec.

so it remains just Watt because the secs delete themselves. I've found it
in my book about Power Eletronics

http://www.amazon.com/Power-Electronics-Converters-Applications-Design/
dp/0471226939/ref=pd_sim_b_title_1

Thank you,
Pasquale.
.