TO220--thin leads--high current--How?
in [Design]
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From: John Larkin on 4 May 2010 10:05 On Mon, 03 May 2010 23:06:40 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Sun, 2 May 2010 14:12:13 -0700 (PDT), "oparr(a)hotmail.com" ><oparr(a)hotmail.com> wrote: > >>> 429?!!! The most ludicrous IR claim I've seen for a D2PAK was 340. >> >>The spec states that 429A is; >> >>"Calculated continuous current based on maximum allowable junction >>temperature. Package limitation current is 160A." >> >>The only thing that makes sense is the packaged limited current IMO. >>This D2PAK has 6 source leads and the entire tab is the drain lead. >> >>On May 2, 3:46�pm, John Larkin wrote: >>> > >Again an infinite heatsink driven by copious amounts of LN2. Gp they use LN2? The appnote cited here said "nucleated boiling liquid." John
From: Tim Williams on 4 May 2010 10:22 "JosephKK" <quiettechblue(a)yahoo.com> wrote in message news:1gdvt5hg195np1oo7f3kj4t72ir37q1btt(a)4ax.com... > IF you can bother to read the datasheet and app notes correctly they use > an _infinite heat sink_ powered by large flow of LN2. They know the > spec is bullshit, but the marketeers (who will never know anything of > reality) insist on the specmanship games. That wouldn't work. http://en.wikipedia.org/wiki/Critical_heat_flux Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: Paul Keinanen on 4 May 2010 10:59 On Tue, 4 May 2010 09:22:00 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"JosephKK" <quiettechblue(a)yahoo.com> wrote in message >news:1gdvt5hg195np1oo7f3kj4t72ir37q1btt(a)4ax.com... >> IF you can bother to read the datasheet and app notes correctly they use >> an _infinite heat sink_ powered by large flow of LN2. They know the >> spec is bullshit, but the marketeers (who will never know anything of >> reality) insist on the specmanship games. This is nothing new :-). For decades power transistor maximum dissipation is specified at 25 C _case_ temperature. The heat sink has some internal thermal resistance, so it must be cooled with some cooler fluid. So in order to get 115 W dissipation on the 2N3055, the heatsink would in practice be cooled by 0 C flowing water. Cooling a semiconductor connected to a large heat sink with LH2 will spread out the heat and the case temperature can be dropped below 0 C and hence the junction can be kept within acceptable values. >That wouldn't work. >http://en.wikipedia.org/wiki/Critical_heat_flux An infinite heat sink would have a large contact surface with the fluid, reducing the power density. With proper orientation and a sufficient liquid flow across the heat sink, the created vapor will be blown away with the stream.
From: John Larkin on 4 May 2010 11:33 On Tue, 4 May 2010 09:22:00 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"JosephKK" <quiettechblue(a)yahoo.com> wrote in message >news:1gdvt5hg195np1oo7f3kj4t72ir37q1btt(a)4ax.com... >> IF you can bother to read the datasheet and app notes correctly they use >> an _infinite heat sink_ powered by large flow of LN2. They know the >> spec is bullshit, but the marketeers (who will never know anything of >> reality) insist on the specmanship games. > >That wouldn't work. >http://en.wikipedia.org/wiki/Critical_heat_flux > >Tim Where can I buy one of those infinite heat sinks? The scrap metal value alone would be ... calculates furiously ... infinite! But where would I store it? I already have an almost-infinite heat sink ftp://jjlarkin.lmi.net/Infinite_Sheet.jpg and it's a nuisance already. John
From: John Larkin on 4 May 2010 12:44
On Mon, 03 May 2010 22:59:36 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Sun, 02 May 2010 14:45:25 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Sun, 2 May 2010 14:18:25 -0700 (PDT), "oparr(a)hotmail.com" >><oparr(a)hotmail.com> wrote: >> >>>>Be safe, don't buy IR. >>> >>>My MOSFETs of choice and I have no "Once bitten, twice shy" rants. >>> >>>On May 2, 3:44�pm, John Larkin wrote: >>>> >> >>I've never been "bitten" by IR specs, because they looked absurd to me >>at first glance. >> >>Do I sound shy to you? >> >>John > >Jerk. See the placement of the quotes in the original. I think the quotes indicate that the writer didn't originate the text. But even cliches have meaning. Tell us about your recent design experiences with power mosfets. Or even your ancient design experiences with power mosfets. John |