September 21, 2009
Tutorial - Sizing a heat sink for a heavy load
about 9 months 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 11 months 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 4 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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