Power MOSFETS
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I am sorry that this is a little of topic but I was wondering if anyone knew
of a good source of ower MOSFETS to drive 12V with up to 18 A and about 216
Watts. I am trying to build a variable speed control from my robot. Thank
you.
[noparse][[/noparse]Non-text portions of this message have been removed]
of a good source of ower MOSFETS to drive 12V with up to 18 A and about 216
Watts. I am trying to build a variable speed control from my robot. Thank
you.
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
> anyone knew
> of a good source of ower MOSFETS to drive 12V with up to 18 A and
> about 216
> Watts. I am trying to build a variable speed control from my
> robot.
Do you mean to say you'll be dropping 12V across the mosfet at 18A, I don't
think so but I might be reading this wrong.
If you turn the MOSFET on and it's acting like a switch, i.e. putting the
load across the input voltage, then you are not dissipating 216W, your
dissipating i2R = 18A*18A*Rds of MOSFET.
If you using it as a series pass regulator, then you could be dropping some
voltage not the full 12 and which case you are dissipating (12V-Vmotor)*18A
(assuming it's always 18A and I don't think it will be.
It all depends on how your using it. If you are indeed dissipating 216W,
then you'll need one heck of a heatsink and it's a lot harder. If you
dissipation is less, you can use a T0-220 package part or T0-3 part and get
common heat sinks. Heatsinking is going to be a real issue in anything other
than using it as a switch.
What type of motor do you have that you are trying to turn into a variable
speed motor ??? DC ??? AC ??? Other ???
In general, I like International Rectifier, www.irf.com.
This link might work ... who knows. It's a large parametric table....
http://ec.irf.com/ec/adirect/ir?cmd=compare&category=52&categoryName=HEXFET+
Power+MOSFETs%2FHEXFET+Power+MOSFET+%28discrete%29%2FN-Channel%2F20V
You can get there from Product Line -> HexFet Power MOSFETS -> Short Form ->
20V parts
I always like overkill, so I like the looks of the IRL3102, rated for 61A,
89W power, 13 milli-ohms Rds (18*18*0.013 = 4.2W if completely on), logic
level drive, etc). Available from Digi-key, PN IRL3102-ND, for 1.70 each.
If you really want overkill, the IRL3502 is rated for 110A, 140W, 7 milliohm
(so about 2.2W if switch is completely on), logic level drive, also
available from digi-key, PN IRL3502-ND for 2.70 each.
Keep in mind if you are using it for anything other than a switch,
heatsinking is critical.
K ... I gotta get back to work ...
John