Question for Mr. Thermo

J

John Fields

Guest
Hey, Bret, since you know a lot about thermodynamics, I've got a
problem here maybe you can help me out with.

I'm stuck with a MOSFET with an Rds(on) of 0.05 ohms and I need to run
20 amps through it all the time.

Well, not all the time, but enough of the time that it might as well
be all the time in that it'll reach thermal equilibrium when it's
working.

It's in a TO-220 package, has a thermal resistance of 1.0C/W from
junction to case, can stand a maximum junction temperature of 175C and
it'll run in an ambient temp of 20C.

Perusing the data available at:

http://www.aavidthermalloy.com/

Which heat sink would you recommend?

Oh, I also have cost constraints, so if you could recommend the least
expensive solution that would be great.

Thank you ever so much. :)

JF
 
On Thu, 14 Aug 2008 18:48:30 -0500, John Fields
<jfields@austininstruments.com> wrote:

Hey, Bret, since you know a lot about thermodynamics, I've got a
problem here maybe you can help me out with.

I'm stuck with a MOSFET with an Rds(on) of 0.05 ohms and I need to run
20 amps through it all the time.

Well, not all the time, but enough of the time that it might as well
be all the time in that it'll reach thermal equilibrium when it's
working.

It's in a TO-220 package, has a thermal resistance of 1.0C/W from
junction to case, can stand a maximum junction temperature of 175C and
it'll run in an ambient temp of 20C.

Perusing the data available at:

http://www.aavidthermalloy.com/

Which heat sink would you recommend?

Oh, I also have cost constraints, so if you could recommend the least
expensive solution that would be great.

Thank you ever so much. :)

JF
After he answers that one, I have some questions about driving
tractors.

John
 

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