Re: LTSpice model for a SiC MOSFET

On 20/05/2025 8:24 am, john larkin wrote:

On Mon, 19 May 2025 14:26:55 -0400, "Edward Rawde" <invalid@invalid.invalid> wrote:
 

"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:100epio$1h4ca$1@dont-email.me...

On 19/05/2025 1:38 pm, john larkin wrote:

On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman
<bill.sloman@ieee.org> wrote:
 

On 19/05/2025 12:15 am, john larkin wrote:

On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman
<bill.sloman@ieee.org> wrote:
 

I'm looking at a problem where somebody wants to step
down a 1kV low current source to 3.3V.
 The Baxandall class-D oscillator could do it, but it
needs a pair 1.7kV MOSFETs for the job. The Infineon SiC
IMH170R450M1 would do it - though it's a much higher
current part (10A) than the job needs (about 1mA).
 I've dived into the Infineon rabbit-hole which promises
LTSpice models, but wasn't able to find one.
 Does anybody know of a similar - ideally cheaper and
smaller - part for which there is an LTSpice model?

 I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my
Pockels Cell driver.
 https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
>
>
 

They do have an LT Spice model library that works.

 Gate drive for SiC parts is a bear. I did it myself, but I
think there are chips for that now.
 There are multi-kilovolt silicon mosfets too.
 Baxandal looks to be inefficient and expensive as a low
power converter. The drain swing is 2x the supply voltage,
and it needs two fets and a difficult custom transformer.

 It isn't going to be inefficient. That configuration is
famous efficient.
 The drain swing is actually 1.67 times the supply voltage,
but it does need two switching devices and a specially wound
transformer (and we know how reluctant you are to design them
or get them made).
 It is probably going to be too expensive for the application,
and we'd be grateful for your insights into a cheaper
alternative. I can't think of one.

 I'm not sure what the specs are, but I have a few ideas.
 One could make a flyback converter with a high-ratio
transformer. Coilcraft makes some, capacitor charging
transformers and CCFLs. There must be crazy cheap Indian or
Chinese CCFL transformers.
 ST makes a 1400v NPN transistor for under a dollar.

 But you can't be bothered to post the part number.

 What you should have said is that you couldn't be bothered to use a
search engine.
 https://www.google.com/search?q=1400v+npn+st
 

 The STN0214 is a cute little 1200 volt SOT-223 for 70 cents at 100. 1400 volts in real life.
 Roger about using search engines to, well, search for things.

John Larkin hasn't paid any attention to the 1.7KV lower limit on the
drain to source voltage. His cavalier attitude to absolute maximun
ratings is well known, and pretty silly.
I did find the IMWH170R450M1 with a google search. It clearly didn't pick up parts that I would have expected it to.
There was a 4.5VkV $200 part that it should have found, but any part that expensive probably isn't going to be off the shelf or widely advertised, so there is an excuse.
--
Bill Sloman, Sydney