Spockie-Tech
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Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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Silicon Carbide mosFET's - Potential new Controller Tech
Hmm.. After commenting on that new integrated controller Aaron posted, I just had a quick check to see what current SOA (State Of the Art) mosFet tech was and found this.
http://www.digikey.com/us/en/ph/Cree/cmf20120d-mosfet.html
Very Interesting.
Rds is *much* higher (*80*mOhm rather than 5mOhm) than the well known 1405 Fet (for Comparison) which means higher internal power losses and increased temperature load for a given operating power level, but the Thermal Cooling Resistance (R(theta)JA) is about 1/3 lower at 40deg/W rather than the 62deg/W of the 1405, meaning it can dump heat into its cooling system a fair bit faster to help.
About 1/2 the gate-charge (nanoCoulombs) requirements means its easier to switch states quickly than the 1405, making the fet drivers have to work less to flip the bridge.. although the much higher Rds would mean you would need a lot of them in parallel to get equivalent low voltage performance.
The lower Operating Junction temperature of 135c vs the 1405's 175c is a bit confusing, from what I read, SiC Fets were supposedly going to be able to survive at ridiculously high operating temperatures without destruction.. Maybe its a limitation of the package rather than the substrate ?
But, the *killer* spec is Vdss.. *1200* volt breakdown vs the 1405's *55* volt !!
OK, Maybe not much excitement for the <36 volt Combat Robot Control world, since the High Rds sucks a bit for Low Volt, High Current applications, but I bet the ESC designers for the E.V. world with their 300+ volt battery packs are drooling about now.
Although at $30+ each, that will probably dampen any major excitement until volumes start to rise and price comes down.. but its good to see a start in this area,
Now hurry up and get me the 600 degree C operating and <10mOhm Rds devices for <$5 I heard about !!
(Actually I also read some stuff that the manufacturers were quite likely to only slowly and gradually bring in this new tech, because they knew it would destroy sales of existing products if not progressively introduced.. *dirtbags*, holding back on new tech to extract maximum $$ from a market. who do they think they are.. Intel ? ) _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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