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September 21, 2009
Tutorial - Sizing a heat sink for a heavy load
about a year ago
You use the 2.7 C/W value from the datasheet, however, these calculations are slightly different than the one in the aavid.com site (http://www.aavid.com/sites/default/files/literature/Aavid-Board-Level-Heatsinks-Catalog.pdf#page=10).
Also, the chart on https://www.sparkfun.com/datasheets/Prototyping/General/PRT-09576-6400BG.pdf is a bit confusing; the arrows refer to both the curves.
In looking at some curves, the value seems to be OK, as the devices are linear:
The smaller 507302B00000G - thermal resistance is 24, on the graph, 5W is about a 100 C rise (20 C/W, roughly)
The 6400 BG - thermal resistance is 2.7, on the graph, 20 W is about a 65 C rise (3.25 C/W, roughly)
The 530001B02500G - thermal resistance is 8.0, on the graph, 20 W is again a 65 C rise (3.25 C/W, roughly), but the curve is non-linear; the 8.0 value seems a bit large too. Note that the 530002B02500G has a thermal resistance of 2.60, but the same graph! Maybe there was an error on the Aavid site?
Any thoughts on this, or am I missing the obvious?
about a year ago
I’ve uploaded the latest library, but still, the pads on the library look like they overlap. Shouldn’t this show up correctly with the new library? When I import the part, the pads look correct.
In bypassing with ‘restring’ to you set min, max, or % to 0? I set % to 0, and things seemed to pass, but it seems like a kludge. Anyone find out what actually is wrong?
I’ve tried uploading this to Oshpark (when not overriding restring), to see what it says, and no errors show up, but I don’t know if Oshpark checks things again. I’m not sure if the clearances are OK. Oshpark’s rules say there is 6 mil spacing.
about 5 years ago
I was working with a system with mixed voltages (5V and 24V), and [yes, you guessed it] seem to have messed up/fried some of my digital outputs (8-13) do to an inadvertent connection.
If I swap out the current AT328 on the Duemilenove I have with this, will all be fine, or is there a buffer chip that has been destroyed as well?
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