Electronics > Projects, Designs, and Technical Stuff

Disapating 750W of MOSFET heat for under $100

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T3sl4co1l:

--- Quote from: wraper on April 11, 2019, 03:31:41 am ---100W per mosfet in linear mode, good luck with that. Hot spots on the die guaranteed.

--- End quote ---

Could you at least look at the datasheet before jerking knees?

I'm rather more concerned with heat sinking a D2PAK.  What's that board made of?  Is there solid copper inside it?

The better solution is to use resistors, which are smaller and cheaper than heatsinks for the same wattage.  There are methods to maintain linear control while switching resistors.

Tim

magic:
Certainly use TO-220, TO-3P, TO-247, TO-264 or similar cases. Do the math for thermal resistance from junction to case, case to sink, sink to air and you will know why.

BTW, I have compiled a table of "typical" case to sink resistances quoted by datasheets for "greased flat surface and normal mounting pressure". Start looking for those numbers in datasheets and you will find them. Realize that at hundreds of watts even case to sink resistance can become significant.

--- Code: ---TO264  .15 °C/W
TO247  .21 °C/W
TO220  .40 °C/W
--- End code ---

You may consider GPU coolers too, some are designed to dissipate 200~300W or more.

For mounting, I would try to use the original mounting system of the sink, with a stiff metal plate where PCB normally goes. No idea how heatpipes would handle reflow soldering.

Siwastaja:
I would question dissipating 750W in semiconductors, or dissipating it at all. What are you building? There might be a better way.

grifftech:
aluminium pot https://www.amazon.com/dp/B001PZBEKE/ref=twister_B002KMJ8GI?_encoding=UTF8&psc=1

tszaboo:
You can either
1.) use a FETs which are qualified for linear operation
2.) test a lot of different FETs and have most of them blow up because thermal runaway, hotspotting, FBSOA, and stuff which is not in the datasheet
3.) use a lot of FETs at low temperature (separate gate drive and feedback)
4.) have someone do the homework for you

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