Hey guys, I’m working on a high power Programmable DC Load. I’m trying to spec out the MOSFETs but have a few questions…
I know most MOSFETs aren’t designed to run in the Linear region due to uneven heating of the internal holes. From what I understand, at lower Id they have negative tempcos as well. I suppose most MOSFETs are used in switching applications, where these problems don’t show up.
After doing some comprehensive research, I’ve found there are several MOSFETs designed specifically for a SOA in the Linear Region. This would be ideal for my DC Load; one issue is that they tend to be rather expensive.
So I’ve been thinking, is there any particular reason you can’t just use a normal MOSFET with PWM control? I’ve been specifically looking at IRF’s DirectFET line, which basically puts the die directly under a metal shell, allowing pretty much the most direct two sided cooling you can get.
To summarize, is there any reason running MOSFETs with PWM instead of DC Servo control wouldn’t work for a DC Load?