AnalogKid has a point, it is rarely
worth designing your own power supply if you can get one off the shelf. You could spend many werks or months learning the fine points already embedded off the shelf supplies.

 

Not having much experience with off-the-shelf power supplies I would guess very few (if any?) are designed to withstand 200°C. Electrolytic caps in most electronic gizmos are rated for 105°C if you're lucky, 85°C if not so lucky.

 

There are +125C supplies in the MIL arena, but not cheap.

ak

 

Well, to make everything worse, this power supply has to fit into a metal, cylindrical casing that has an inner diameter of 33mm. The PCB I am designing onto will be about 176mm long and 28mm wide. The tallest any given component can be is only about 10mm. So, yes. Unfortunately, we have to design our own. No one is going to have one just off the shelf which will fit the dimensions we need while being reliable at 200C.

The upside is that, at the rate I am going, I will be able to write the book on designing high temp rated SMPSs... well... give me another 3 months on this problem anyway and then look out for my publication!

I think I've learned above all else that I want to be in R&D. Getting paid to learn is far more satisfying than paying my current tuition rates.

 

At +200C the magnetics will change.

ak

 

Jackie;

The device you are prototyping (LT8316) has an example of a 94% efficient isolated supply on page 21, figure 5.
They also have a discussion of snubbers on page 17. This would reduce the ringing some. You might also look at your current design, a snubber may help.

Charles

 

This is from the datasheet for LT3816, Absolute Max section:

Operating Junction Temperature (Note 2) LT8316E, LT8316I.............................. −40°C to 125°C
Storage Temperature Range .................. −65°C to 150°C

How is that going to operate at 200C?
Are you sure about the 200C?

Bob

 

They may have to go through a selection process to find units that can operate at that temperature. Some silicon ICs can operate at 300°C.
A tutorial is available here: http://www.extremetemperatureelectronics.com/index.html