b...@evoria.net said: > The one thing that is missing is how to quantify the heat sink needs for a > linear regulator. Any thoughts? IOW, is there some way to project how many > square inches of heat sink needed for X watts to dissipate?
In the simple minded case, you can add up the (series) resistance. The units are degrees/watt. Chips and heat sinks will have a parameter in the data sheet: often Theta something-or-other. Mumble, round up for the connection between the chip and heat sink. With fins-to-air, it depends on the velocity of air. With a fan, that might be a constant. If you are depending upon convection, it gets messy, aka nonlinear. (I think, but don't have a good URL.) If you are using the PC board rather than a heat sink, the key factor is the size of the copper plane that the chip is soldered to. National had several app-notes with numbers for various chunks of copper. With typical (digital) multilayer boards, you can also help a lot by using many vias to connect the small surface copper planelet to the ground plane(s) internal to the PCB. -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.