Quote:
Originally Posted by MPaulHolmes
Hi Flatmann! I'll add some labels to the next version of the help file, so people actually know which wires are which. Sorry about that!
Hey, I priced type 3 anodizing for the 1"x2"x10" aluminum block that I bought today. It costs $3 to anodize! hahaha. Isnt' that funny? I thought it would be more like $50 or something. Of course, the bad news is there is a $150 minimum.. hehe. So, that means I should do 50 heat spreaders! That's a lot...
I milled one of the faces of it so it's almost mirror smooth. I'll do the other faces tomorrow (just 2 more that matter). I think this is going to work really really well for taking the heat away from the mosfets. They can dissipate 1600 watts each for crying out loud! Isn't that ridiculous? The legs are good to 160amp.
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Great pricing on the anodizing! Can't wait to see the pictures.
Watch out for MOSFET power and current ratings, they get tricky. That 1670W is only valid if the case of the MOSFET is held at 25-degrees C. That's almost impossible at over a few watts with anything less than really silly-expensive immersed liquid or spray cooling. With really good heat-sinking, you could do about 100W-150W continuously with each MOSFET.
Other limits and specs are covered in the data sheet but particularly important ones are the Thermal Resistance, Gate Charge, Foward-Bias Safe Operating Area (to see if they can handle the heat generated when being turned on and off, i.e., when they're passing through the high-resistance "linear" operating region of the MOSFET) and the Maximum Transient Thermal Impedance. Some of the calculations for these can get pretty ugly, pretty darn quick. Sometimes it's just better to hook the suckers up, watch for smoke, and take some measurements (if said smoke doesn't appear).
