Power Semiconductors With 5% Duty Cycle
Power Semiconductors With 5% Duty Cycle
(OP)
Power Semiconductors With 5% Duty Cycle
I’m doing some heat transfer analysis on power semiconductors with a 5% duty cycle at continues pulse. I know that for preliminary the Average Power (heat) dissipated will be Peak Power x Duty Cycle. Because it is 5% duty cycle, the device will heat up and then cool down with each pulse so the temp rise will be the same through the time used.
I’m locking horns with my manager about Peak Power. He wants me to also do an analysis using Peak Power. I guess my question is “Should the Average Power be enough for the analysis?” and “Why look at Peak Power anyway, does it matter in a 5% duty cycle?".
Thanks in advance for your time and effort.
I’m doing some heat transfer analysis on power semiconductors with a 5% duty cycle at continues pulse. I know that for preliminary the Average Power (heat) dissipated will be Peak Power x Duty Cycle. Because it is 5% duty cycle, the device will heat up and then cool down with each pulse so the temp rise will be the same through the time used.
I’m locking horns with my manager about Peak Power. He wants me to also do an analysis using Peak Power. I guess my question is “Should the Average Power be enough for the analysis?” and “Why look at Peak Power anyway, does it matter in a 5% duty cycle?".
Thanks in advance for your time and effort.
Go Mechanical Engineering
Tobalcane





RE: Power Semiconductors With 5% Duty Cycle
The junction temp might get hot enough to cause metal migration into the junction, resulting in a shorted junction.
TTFN
RE: Power Semiconductors With 5% Duty Cycle
Go Mechanical Engineering
Tobalcane
RE: Power Semiconductors With 5% Duty Cycle
RE: Power Semiconductors With 5% Duty Cycle
Thanks for responding. Now why do I have to look at peak current densities?
Go Mechanical Engineering
Tobalcane
RE: Power Semiconductors With 5% Duty Cycle
TTFN
RE: Power Semiconductors With 5% Duty Cycle
Will this happen near or above the max Tj? Is this also a function of time? As in will this happen in seconds or days of continues use?
I just wan to see if I am thinking right. When I do a transient analysis using the Peak Power, would the temperature rise come to equilibrium close to a steady state analysis using the Average Power?
Go Mechanical Engineering
Tobalcane
RE: Power Semiconductors With 5% Duty Cycle
The semiconductor temperature-time behavior is dependent on its thermal mass and thermal isolation, so it may, or may not, reach anything close to equilibrium.
TTFN
RE: Power Semiconductors With 5% Duty Cycle
RE: Power Semiconductors With 5% Duty Cycle
http://www.irf.com/indexsw.html
and search for, say, IRF250. Look at figure 11 in the data sheet. You should also be able to find an app note on the subject.