TO220--thin leads--high current--How?
in [Design]
|
From: JosephKK on 4 May 2010 01:57 On Sun, 02 May 2010 12:44:00 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Sun, 2 May 2010 10:42:44 -0700 (PDT), "oparr(a)hotmail.com" ><oparr(a)hotmail.com> wrote: > >>>Continuous 80 amps into a TO220 is insane. >> >>If you do a parametric search on MOSFETs with continuous drain of 80A >>or more and with TO220 case it will return several manufacturers, not >>just IR. Me thinks you're making a mountain out of a molehill in >>singling out IR specs. >> >>>And the 200 watt dissipation spec is absurd. >> >>Ditto on Power Max 200W and over. >> >> >>On May 2, 10:43 am, John Larkin >><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>> > >IR published one brochure where they claimed that a D2PAK was good for >340 amps. > >Having parts and boards blow up, and source leads vaporize, is not a >"molehill." > >One has to read the IR datasheets very carefully, including the SOAR >curves, to figure out how much current and power they can reasonably >stand. If you read the headlines or the abs max specs on the >datasheet, and design around that, things *will* fail. I bet a lot of >beginners get "burned" that way. > >What's the point of them headlining 120 amps for the silicon and then >putting a tiny footnote stating that it's "package limited" to 80, >when it might be safe at 30? > >Be safe, don't buy IR. > >John 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.
From: JosephKK on 4 May 2010 01:59 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.
From: JosephKK on 4 May 2010 02:06 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.
From: JosephKK on 4 May 2010 02:28 On Mon, 3 May 2010 18:09:56 -0700 (PDT), MooseFET <kensmith(a)rahul.net> wrote: >On May 3, 10:24 am, "Tim Williams" <tmoran...(a)charter.net> wrote: >> "MooseFET" <kensm...(a)rahul.net> wrote in message >> >> news:a255d645-99e3-4207-8aad-dbe3d49c2988(a)h20g2000prn.googlegroups.com... >> >> > There is some poorly documented impedance between the gate leg >> > and the actual controlling gate element. >> >> In other words, gate spreading resistance. And maybe some inductance, and >> other squirrelies, depending on how detailed you want to get. More >> important also is the source lead inductance (which is sometimes specified >> at 5nH or so). >> >> I get the impression that spreading resistance has dropped over the years. >> Back in the day, you didn't see FETs spec'd for very impressive rise/fall >> times. But they also used fairly large Rg's, so is it just that they didn't >> try? > >Way back when there was little point in going below a 20 Ohm gate >driver. >Today that is very much no longer the case. > >The funny thing is that the Siliconix parts of the past had low gate >resistance can worked as very nice class D RF stages at 16MHz. I >could >get a couple of watts out of a VN88 with good efficiency. Class D or class S? > >> >> > The reverse transfer capacitance is not a constant with voltage or >> > time. It conspires to stop the gate electrode from moving just at >> > exactly the time when the conditions are the worst from a power >> > point of view. >> >> Cgd is fun. >> >> http://myweb.msoe.edu/williamstm/Images/PFC_Gate1.png > >I've had it eat a driver stage for lunch
From: John Larkin on 4 May 2010 10:03
On Mon, 03 May 2010 22:57:14 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Sun, 02 May 2010 12:44:00 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Sun, 2 May 2010 10:42:44 -0700 (PDT), "oparr(a)hotmail.com" >><oparr(a)hotmail.com> wrote: >> >>>>Continuous 80 amps into a TO220 is insane. >>> >>>If you do a parametric search on MOSFETs with continuous drain of 80A >>>or more and with TO220 case it will return several manufacturers, not >>>just IR. Me thinks you're making a mountain out of a molehill in >>>singling out IR specs. >>> >>>>And the 200 watt dissipation spec is absurd. >>> >>>Ditto on Power Max 200W and over. >>> >>> >>>On May 2, 10:43�am, John Larkin >>><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >> >>IR published one brochure where they claimed that a D2PAK was good for >>340 amps. >> >>Having parts and boards blow up, and source leads vaporize, is not a >>"molehill." >> >>One has to read the IR datasheets very carefully, including the SOAR >>curves, to figure out how much current and power they can reasonably >>stand. If you read the headlines or the abs max specs on the >>datasheet, and design around that, things *will* fail. I bet a lot of >>beginners get "burned" that way. >> >>What's the point of them headlining 120 amps for the silicon and then >>putting a tiny footnote stating that it's "package limited" to 80, >>when it might be safe at 30? >> >>Be safe, don't buy IR. >> >>John > >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. And I insist on not buying their parts. So everybody, even you, is happy. John |