IR is insane
in [Design]
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From: John Fields on 20 Mar 2010 21:30 On Sat, 20 Mar 2010 13:23:13 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Fields wrote: >> On Sat, 20 Mar 2010 10:56:18 -0700, John Larkin >> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>> On Sat, 20 Mar 2010 10:29:37 -0700, Archimedes' Lever >>> <OneBigLever(a)InfiniteSeries.Org> wrote: >>> >>>> On Sat, 20 Mar 2010 10:06:13 -0700, John Larkin >>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>> I haven't done the math on this, >>>> We can tell. >>>> >>>>> but I suspect the source lead would >>>>> vaporize at 195 amps, much less 340. >>>> >>>> You always seem to have suspicions. We have a few about you. >>>> >>>>> If it were immersed in a boiling >>>>> liquid, it would probably be OK. I think that's how they test them. >>>> Why would the liquid have to be boiling, Johnny? You *think* that is >>>> how they test them? It is clear that you ASSume, as opposed to thinking. >>> Someone in this thread provided a link to an IR paper that discussed >>> the boiling liquid test procedure. Did you read it? >>> >>> They said in that paper that *some* of their parts are tested this >>> way. I can't tell which parts. Can you? >>> >>> Boiling liquid carries away far more heat than still or even flowing >>> liquid. >> >> --- >> Not just boiling liquid, John, _nucleate_ boiling. >> > >Ain't that "nuculate"? :-) --- Not any more... it seems what we've got now is someone who thinks an electron is a voting machine. --- >> There is a clear distinction between the two as described here: >> >> http://en.wikipedia.org/wiki/Nucleate_boiling >> > >IOW a really realistic method of cooling a D2PAK transistor :-) --- Depends... JF
From: JosephKK on 21 Mar 2010 13:08 On Thu, 18 Mar 2010 23:44:48 -0700 (PDT), George Herold <ggherold(a)gmail.com> wrote: >On Mar 18, 8:19 pm, John Larkin ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> On Thu, 18 Mar 2010 18:02:27 -0500, Damon Hill >> >> <damon16...(a)comcast.not> wrote: >> >John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote in >> >news:cpb5q5p2013r34ainnmcrdfjml4ifvp03g(a)4ax.com: >> >> >> Just got a short-form IR mosfet thing in the mail. >> >> >> They have a PQFN 5x6 mm package they rate at 104 amps. And a D2PAK >> >> rated for 340 amps. >> >> >Hmm. Define 'continuous'. (a >very< short pulse rating I'd believe) >> >> The flyer doesn't mention pulsing. The D2PAK datasheet pulsed current >> rating is 1080 amps. >> >> http://www.irf.com/product-info/datasheets/data/irfs3006pbf.pdf >> >> The flyer claims 340 amps. The datasheet says 270 amps but "package >> limited" to 195. I don't believe any of them. >> >> The datasheet also claims 375 watts power dissipation... in a D2PAK! >> >> John > >I wonder if they are dunking it and it's heatsink into liquid >nitrogen. One figure in the data sheet showed the on resistance as a >function of temperature. The minimum temp was -60 C with a current of >175 Amps. > >George H. That sounds close to the triple point of CO2. I'll bet the higher values were done in liquid nitrogen.
From: JosephKK on 21 Mar 2010 13:14 On Fri, 19 Mar 2010 11:05:14 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Fri, 19 Mar 2010 07:16:29 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Thu, 18 Mar 2010 23:44:48 -0700 (PDT), George Herold >><ggherold(a)gmail.com> wrote: >> >>>On Mar 18, 8:19 pm, John Larkin >>><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> On Thu, 18 Mar 2010 18:02:27 -0500, Damon Hill >>>> >>>> <damon16...(a)comcast.not> wrote: >>>> >John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote in >>>> >news:cpb5q5p2013r34ainnmcrdfjml4ifvp03g(a)4ax.com: >>>> >>>> >> Just got a short-form IR mosfet thing in the mail. >>>> >>>> >> They have a PQFN 5x6 mm package they rate at 104 amps. And a D2PAK >>>> >> rated for 340 amps. >>>> >>>> >Hmm. Define 'continuous'. (a >very< short pulse rating I'd believe) >>>> >>>> The flyer doesn't mention pulsing. The D2PAK datasheet pulsed current >>>> rating is 1080 amps. >>>> >>>> http://www.irf.com/product-info/datasheets/data/irfs3006pbf.pdf >>>> >>>> The flyer claims 340 amps. The datasheet says 270 amps but "package >>>> limited" to 195. I don't believe any of them. >>>> >>>> The datasheet also claims 375 watts power dissipation... in a D2PAK! >>>> >>>> John >>> >>>I wonder if they are dunking it and it's heatsink into liquid >>>nitrogen. One figure in the data sheet showed the on resistance as a >>>function of temperature. The minimum temp was -60 C with a current of >>>175 Amps. >>> >>>George H. >> >>IR does insane things. The flyer I got spec'd the max current (340 >>amps!) and Rds-on different from the part datasheet (270 amps, or 195 >>amps "package limited")... all or which are preposterous for a dpak. >> >>When people play games like that, I don't buy their parts. > >--- >Oh, well, it's your loss... > >60Vdss, Rds(on)max 2.5milliohms, 375 watts @25C Tc, it's a nice part. > >JF Well JF, what is the typical theta(jc) of a dpak? This sounds like a really crazy infinite heat sink driven by LN2.
From: JosephKK on 21 Mar 2010 13:43 On Sat, 20 Mar 2010 18:09:39 -0500, "krw(a)att.bizzzzzzzzzzzz" <krw(a)att.bizzzzzzzzzzzz> wrote: >On Sat, 20 Mar 2010 12:12:14 -0700, Archimedes' Lever ><OneBigLever(a)InfiniteSeries.Org> wrote: > >>On Sat, 20 Mar 2010 10:56:18 -0700, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>Boiling liquid carries away far more heat than still or even flowing >>>liquid. Since IR cheats as hard as they can, we can assume they used >>>boiling liquid. I fact, they say so. >> >> >> Chilled fluorinert does not need to be boiling to have thermal >>efficiency. > >Wrong again, AlwaysWrong. How do you think Fluorinert works? By magic? While i have seen Flourinert cooling maybe half a dozen times, only once was it used in phase change mode. I mostly saw circulated chilled liquid baths. Works real good for temperature stabilizing standard resistors.
From: WarmUnderbelly on 21 Mar 2010 14:52
On Sun, 21 Mar 2010 10:43:02 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Sat, 20 Mar 2010 18:09:39 -0500, "krw(a)att.bizzzzzzzzzzzz" <krw(a)att.bizzzzzzzzzzzz> wrote: > >>On Sat, 20 Mar 2010 12:12:14 -0700, Archimedes' Lever >><OneBigLever(a)InfiniteSeries.Org> wrote: >> >>>On Sat, 20 Mar 2010 10:56:18 -0700, John Larkin >>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>Boiling liquid carries away far more heat than still or even flowing >>>>liquid. Since IR cheats as hard as they can, we can assume they used >>>>boiling liquid. I fact, they say so. >>> >>> >>> Chilled fluorinert does not need to be boiling to have thermal >>>efficiency. >> >>Wrong again, AlwaysWrong. How do you think Fluorinert works? By magic? > >While i have seen Flourinert cooling maybe half a dozen times, only once was >it used in phase change mode. I mostly saw circulated chilled liquid baths. >Works real good for temperature stabilizing standard resistors. It is also a good media, if chilled, for cooling a PC for the overclocker crowd. I would like to put a PC motherboard in a fish tank full of it to freak people out with. |