Hi, I have been trying for several weeks off and on to get my 100 VDC variable power supply to work with a 300ma inductive load. I have to be able to set it for 55V. When I do the output transistor gets hot (190F after 5 minutes). Its like the attached power supply circuit, but with a darlington set up (like attached). Ive tried switching to a mosfet, taking out the darlington set up (2 transistors). I still got hot. Not sure if a bootstrap capacitor (attached) would do anything, Im not switching or oscillating the input. The only thing that helped is paralleling the output transistors, but ended up with one getting hotter than the other, unless I had a separate drive transistor for each. Can anyone help with this? I don't want a ginormous heatsink. There must be something Im missing.
Attachments
-
14.4 KB Views: 36
-
73.2 KB Views: 29
-
78.5 KB Views: 30
-
28.5 KB Views: 28