IR is insane
in [Design]
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From: Tim Williams on 19 Mar 2010 00:02 <a7yvm109gf5d1(a)netzero.com> wrote in message news:41cb68b6-1386-4953-9cfa-21bc6c6582c4(a)l25g2000yqd.googlegroups.com... > Wiki claims "hundreds of amps" for the secondary of the transformer > inside those Weller soldering guns. > So you got an easy source of amps there. Seems to me if the > constriction in the copper bar that serves as the iron element gets > hot, those tiny pins should get hot too? But nobody uses their soldering iron while submerged in nucleated boiling fluid. In fact, it would be quite impossible to use -- I'd guess such an "IR-rated" soldering iron would be good for 10kW or more, continuous. And like the transistor, that doesn't mean you want to actually use it at that power level on a circuit board. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: WarmUnderbelly on 19 Mar 2010 00:19 On Thu, 18 Mar 2010 23:02:19 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: ><a7yvm109gf5d1(a)netzero.com> wrote in message >news:41cb68b6-1386-4953-9cfa-21bc6c6582c4(a)l25g2000yqd.googlegroups.com... >> Wiki claims "hundreds of amps" for the secondary of the transformer >> inside those Weller soldering guns. >> So you got an easy source of amps there. Seems to me if the >> constriction in the copper bar that serves as the iron element gets >> hot, those tiny pins should get hot too? > >But nobody uses their soldering iron while submerged in nucleated boiling >fluid. > >In fact, it would be quite impossible to use -- I'd guess such an "IR-rated" >soldering iron would be good for 10kW or more, continuous. And like the >transistor, that doesn't mean you want to actually use it at that power >level on a circuit board. > >Tim I am sure that you have seen the shrunken quarters. Some pretty wild stuff. http://205.243.100.155/frames/shrinkergallery.html
From: Muzaffer Kal on 19 Mar 2010 02:32 On Thu, 18 Mar 2010 15:58:08 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >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. > >John The only thing that actually matters is whether you can stay under the power curve of I^2*Rdson(T). At 1milliohm max 340 Amps gives you 115 W. You need to make sure to check the C/W rating of the package and cool it enough. -- Muzaffer Kal DSPIA INC. ASIC/FPGA Design Services http://www.dspia.com
From: George Herold on 19 Mar 2010 02:44 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.
From: Robert Baer on 19 Mar 2010 17:16
John Larkin wrote: > 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. > > John > ....in that case, i have some #30 wire rated at 1,000 amps and will guarantee it or double your money back! |