Dave Celsnak wrote:

> To heat sink, or not to heat sink, that is the question.
>
> I have a 7805, 220 style case running my PIC board.  I am using a total of
> 0.700 amps.  Do I need to heat sink the 220 case/ 5v regulator??????
> (This is a 3.0 amp device!)

The current rating is the maximum current it can handle. You have to
limit the power dissipated.

As an example, consider the difference between running your regulator
from 20V, and 9V

Power dissipated :
        9V : (9-5)*.7 = 2.8W = Very hot - I'd use a big heat sink.
        20V : (20-5)*.7 = 10.5W = Soldering iron.

Consider using a switch mode supply.

--
Friendly Regards

Tjaart van der Walt
mailto:tjaart@wasp.co.za

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