I need a reality check here. :-)
Am I reading the FBSOA graph (Fig. 11) correctly for this IXYS MOSFET?
It looks if I wanted to use it as a 100% duty-cycle switch (on for seconds to minutes at a time), I'm limited to a Vds of about 25V? Even if my current level is low, say 1A? I've never seen the Vds rating drop with increasing pulse width before but I've always used Intl. Rect. FETs and, so far, each one's Vds max has been the same for various pulse widths in their SOA graphs.
When running a MOSFET as a basic power switch (essentially 100% duty-cycle), I've always run it without regard to the SOA as long as my Vds was comfortably below the rated max, I keep the junction temp low enough, etc. I'm wondering now if that's not a real good idea.
How can I extrapolate a DC curve for something like an IRF1405?
Or do I not have to worry worry about 100% duty cycle operation for the IRF1405 because, unlike the IXYS FET, the IR FET's Vds rating doesn't change with pulse width?
Thanks! John
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