TO220--thin leads--high current--How?
in [Design]
|
From: Jamie on 2 May 2010 17:11 John Larkin wrote: > On Sun, 02 May 2010 14:33:49 -0400, Spehro Pefhany > <speffSNIP(a)interlogDOTyou.knowwhat> wrote: > > >>On Sun, 2 May 2010 12:58:24 -0500, the renowned "Tim Williams" >><tmoranwms(a)charter.net> wrote: >> >> >>>I once accidentially burned out a capacitor lead at 50A. It was 0.6mm >>>diameter, active section about 2-3mm long. >>> >>>I was testing a high current power supply, which was operating happily at >>>50A, with unusually low output voltage. Ten seconds later, *phut*, poof. >>>;-) My fault for clipping a large alligator clip to a fairly small >>>capacitor. >>> >>>The only thing you need to know about MOSFETs is use them at half rated >>>current. As an added bonus, the Rds(on) is relatively small, so you need >>>even less heatsinking. >>> >>>Tim >> >>So, in the case of a D2Pak rated at 429A (asterisk) continuous or >>1640A pulsed (160A package limit) would you run it at 820A, 214.5A or >>80A? >> >> > > > 429?!!! The most ludicrous IR claim I've seen for a D2PAK was 340. > > A new record! > > John > > John, we have a piece of gear at work that uses IR fets at their maximum because of space constraint of where it slips into a rack. These are high current components that would normally vaporize the leads of its case. How ever, the leads are not soldered in place, instead, they are clamped into a much heavier load capacity connection and the body of the case up against the clamp. There are no visible leads. It has an extended heat sink on the back that does get a little warm.. I can't recall the IR part number but it's well over 150 AMP with very low (Ron) and does operate at near max 75% of the time when the machine is running. We've only had one incident of losing a Fet and that we think was caused my mother nature.. I may also add that losing that FET was a nice event. The blow out physically destroyed a near by cap.
From: oparr on 2 May 2010 17:12 > 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: >
From: oparr on 2 May 2010 17:18 >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: >
From: John Larkin on 2 May 2010 17:45 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
From: John Larkin on 2 May 2010 17:49
On Sun, 02 May 2010 17:11:18 -0400, Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote: >John Larkin wrote: > >> On Sun, 02 May 2010 14:33:49 -0400, Spehro Pefhany >> <speffSNIP(a)interlogDOTyou.knowwhat> wrote: >> >> >>>On Sun, 2 May 2010 12:58:24 -0500, the renowned "Tim Williams" >>><tmoranwms(a)charter.net> wrote: >>> >>> >>>>I once accidentially burned out a capacitor lead at 50A. It was 0.6mm >>>>diameter, active section about 2-3mm long. >>>> >>>>I was testing a high current power supply, which was operating happily at >>>>50A, with unusually low output voltage. Ten seconds later, *phut*, poof. >>>>;-) My fault for clipping a large alligator clip to a fairly small >>>>capacitor. >>>> >>>>The only thing you need to know about MOSFETs is use them at half rated >>>>current. As an added bonus, the Rds(on) is relatively small, so you need >>>>even less heatsinking. >>>> >>>>Tim >>> >>>So, in the case of a D2Pak rated at 429A (asterisk) continuous or >>>1640A pulsed (160A package limit) would you run it at 820A, 214.5A or >>>80A? >>> >>> >> >> >> 429?!!! The most ludicrous IR claim I've seen for a D2PAK was 340. >> >> A new record! >> >> John >> >> >John, we have a piece of gear at work that uses IR fets at their maximum >because of space constraint of where it slips into a rack. > These are high current components that would normally vaporize the >leads of its case. How ever, the leads are not soldered in place, >instead, they are clamped into a much heavier load capacity >connection and the body of the case up against the clamp. There are no >visible leads. It has an extended heat sink on the back that does get >a little warm.. I can't recall the IR part number but it's well over >150 AMP with very low (Ron) and does operate at near max 75% of the time >when the machine is running. We've only had one incident of losing a >Fet and that we think was caused my mother nature.. I may also add that >losing that FET was a nice event. The blow out physically destroyed a >near by cap. > > > What package are you using? At how much continuous current? Soldering or clamping the leads to something massive, very close to the plastic body, will obviously help keep the leads from fusing. John |