TO220--thin leads--high current--How?
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From: vkj on 2 May 2010 09:59 I have a somewhat basic question. I am using a high current MOSFET (IRF3205) rated at 80A cont. Acc to convential wisdom for a copper conductor at about 4A/sqmm ct. dens. the conductor shd be about 20 sqmm, while the TO220 lead is a small fraction of that. At 80A this thin lead would probably fuse. How does one actually use this package? Thanks, vkj --------------------------------------- Posted through http://www.Electronics-Related.com
From: Phil Allison on 2 May 2010 10:26 "vkj" >I have a somewhat basic question. I am using a high current MOSFET > (IRF3205) rated at 80A cont. Acc to convential wisdom for a copper > conductor at about 4A/sqmm ct. dens. ** Where did you get that nonsense figure ?? The fusing current of 1sq mm Cu wire is just under 100 amps. > At 80A this thin lead would probably fuse. ** Not likely if soldered down to a PCB track. ..... Phil
From: John Larkin on 2 May 2010 10:43 On Sun, 02 May 2010 08:59:14 -0500, "vkj" <tranquine(a)n_o_s_p_a_m.n_o_s_p_a_m.gmail.com> wrote: >I have a somewhat basic question. I am using a high current MOSFET >(IRF3205) rated at 80A cont. Acc to convential wisdom for a copper >conductor at about 4A/sqmm ct. dens. the conductor shd be about 20 sqmm, >while the TO220 lead is a small fraction of that. At 80A this thin lead >would probably fuse. > >How does one actually use this package? > >Thanks, > >vkj > I have delivered more than one rant on the deceptive nature of IR mosfet specs. Apparently they test them in boiling liquid, which keeps the leads from fusing. Seriously. Their datasheet is a mess. Continuous Id is listed as 110(footnote), 80, and 75 amps. And the 200 watt dissipation spec is absurd. I never buy IR parts because they are such fools and/or liars. Continuous 80 amps into a TO220 is insane. John
From: Michael Karas on 2 May 2010 11:00 In article <a93rt5p9mdaf97ejj31kvs4d6v38utud50(a)4ax.com>, jjlarkin(a)highNOTlandTHIStechnologyPART.com says... > > > Continuous 80 amps into a TO220 is insane. > > John Real world experience here. I once did a design of a motor driver with T0220 parts mounted vertical from a heat sink right down into a plated through hole. The FETs were capable of handling the "design to" current specification I was given. However when the motor was exposed to stall conditions the leads of the T0200 would completely vaporize. The PSU was rated at 80A that was current limited so the fusing was happening at somewhat over 80A (what ever design margin was used in the PSU for its limit threshold). -- - mkaras
From: oparr on 2 May 2010 13:42
>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: > |