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Registered Member #1749
Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497
It is a new thing to me but i was wondering if i could attach 5 mosfet's together to make one 300A mosfet like so if i can it would be cool if i can get some advice i already put it together.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Well, i do not know much about it but i know that you would just parallel all of the leads. I think it will work, but it will not switch well at high frequencies. If you do this, you will have to make sure that all gate resistors(if there are any, which you should use them) are perfectly matched.
Do not expect them to all switch perfectly simultaneously, or to have the same max current rating that you'd expect due to the different gate capacitances, therefor different switching times. You will probably also have to deal with one mosfet taking more of the load(caused by lower Rds on) and heating more rapidly.
Registered Member #1790
Joined: Fri Oct 31 2008, 10:10AM
Location: Sydney, Australia
Posts: 40
All you do is place them all in parralel and use a 1 0hm or so resistor on the gate and drive it with a Gate Drive chip like a ucc or tc, it will how ever not switch at high frequencies.
Gate resistors make sure that you are feeding the needed amount of current to the gate.
And could you also care to explain how this is a project.
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
I'd just like to mention that your diagram has the devices wired in series, which would increase maximum voltage, not parallel for more current.
Paralleling MOSFETs is not exactly orthodox but someone here has shown a commercial inverter with a fullbridge of 2 parallel MOSFETs per leg.
I don't think it would work with five devices, however. As mentioned, you get a horde of nasty side effects like thermal runaway, different turn-on times, current sharing, etc.
Registered Member #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
Paralleling mosfets is fine provided you derate them accordingly and are not switching peak currents that exceed the rating for one device. Because the Rds goes up with temp, they naturally share current.
If you really need to switch 300A (or even anything close to that) im willing to guess you will have other problems besides the parallel configuration. This is not trivial stuff.
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5 60A mosfets
