How about pumped liquid sodium?
John
How about pumped liquid sodium?
John
Seriously, IR tests some fets in some exotic boiling liquid coolant.
And the data sheet might say in huge type 300 AMPS where the fine print says that the leads and wire bonds can't handle that.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
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IRF has an appnote on how testing is done, whole assembly submerged in a li quid that boils at 25'C
Can't think of a reason to have done such a thing -- power amps were always in the kW range (PA systems, shaker tables), or switching (VFDs have used switching devices since the beginning: thyratrons, then SCRs), or RF (an SS RF PA might be a bunch of ~kW modules linked together).
The largest I know of are also the, well, largest: MW commutating IGBT modules, SCRs, IGCTs and such. They "only" go up to ~10kW. (High efficiency!)
Tubes (the hard vacuum kind) were competitive, until relatively recently, at very high monolithic power dissipations (1MW), thanks to economy of scale I suppose, in a couple applications where transistors weren't yet practical. VoA was tube for a long time. (I think probably the only place tubes survive at such a scale is in research particle accelerators, where klystrons are pulsed at near-MW levels. Hmm, radar sets should be up there as well, the simpler and more powerful ones -- but they'll be more compact thanks to the efficiency of the magnetron. Synthetic aperture radar I imagine is all SS?)
These days, it's far cheaper to switch the energy away, rather than dissipate it. If you think you need brute force dissipation, tell me about it and I'll show you how it can be done without. ;-) (Or, at least, with less.)
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design
That was totally uncalled for. Someone in Africa could have benefited from those transistors.
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Probably. Too far back in time to remember. They revealed in the same issue that it was a joke - on another page, I think.
That is not only misleading but disgusting as well. Who cares what the silicon can do it the package can't handle it?
Agreed. At best it might be an interesting snippet in a research article.
Bet it runs very hot.
ExFets, yeah that's been linked here a few times. if you go digging there's a back story.
Someone in Africa is probably benefitting the research done on those parts.
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That lower rating for flower power is stupid; Indium is NOT needed for proper doping, and that results in a higher allowable Tj.
Yeah, it's just a figure of merit by keeping the case at 25C.
Based on mximum die temperature and Rjc, the bigger the die, the better. And more expensive of course.
boB
Unless you buy old. IRFPxxx have humongous dies, and cost dimes on the dollar compared to new ones. Go figure. :-)
I mean, you won't find 1000W MAX247s in the old numbers, but it's more than practical to dump 100W per part, in real world conditions. If you don't mind the humongous capacitances.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design
Interesting... And RdsOn has come down from a long time ago. Too bad that MOSFETs (HV especially) have that awful intrinsic diode in them !
I was happy to have Rjc come down to, and then below, 1.0 C/W so it was easier to calculate peak junction temperature from peak dissipation and case temperature.
boB
Since SuperJunction took over, high voltage (over 200V or thereabouts) MOSFETs have been on par with low voltage ones, as they always should've been. (Old ones had quadratic Rds(on) versus Vds(max), so MOSFETs over maybe 500V were noticeably, and increasingly, crap.) I used to say you couldn't get a single MOSFET that would handle what a certain very average type of vacuum tube could do (namely, sweep tubes: about 50 ohms "on", ~6kV off rating). At the time, the best offer was a 2.5kV, 250 ohm MOSFET by IXYS -- a specialty for sure! Nowadays, however, they're all the way up to
4.5kV (it's hard to do much more in silicon, period: the hottest SCRs and IGBTs push 6kV) and below 40 ohms. Big transistors, no doubt, but not at all challenged by vacuum tubes, even discounting the pesky screen and heater supplies. ;-) (They're cheaper too: sweeps are surprisingly expensive due to demand from repairs, audiophile and HAM radio applications.)Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design
Mitsubishi (IMHO is the leader in high power switches) have some packages that can switch 1.2kV & conduct 1 kA, pulse 2kA and dissipate > 5kW.
Svetlana seems to still manufacture the EL-509:
They aren't that cheap at around $25 per
Some of their parts would desolder, or melt, their own leads if they weren't submerged in the liquid. Things like 200 amps from a dpak.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I salvaged a couple MG300J1US1 IGBTs.
600V 300 amp DC, 600 amp 1ms pulse, 1200 Watt rating. A bit slow by today's specs. Probably OK if I ever get the gumption to complete a Tesla coil.Mikek
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