Quote Originally Posted by lerameur View Post
it is TO-220,
by the way I once saw a sheet with all the packages types on the digi key web site, I cant seem to find it anymore. Would you have a similar sheet?
But instead of using 7809 and 7805, I think I will use a 2amp or maybe a 3 amp regulator it wont cost more.
k
If you pull up a search on digikey for 'regulator', 'fixed', '5v', it should be able to show you pretty much all of the packages they have available.

Quite frankly, there's got to be something else going on. 1 watt on a TO-220 7805 isn't that much...and again, quite frankly, if the regulator isn't shutting down, I don't think it's getting too hot to worry about. The datasheet I've got for the TO-220 case shows a temp rise of 65C/watt without a heatseak (junction to air) and a max operating temp of +125C. That tells me that something just short of 2watts is safe. You're dumping 1.54watts, 1.54 x 65 = 100C. That's hot, but not really that HOT...especially if you've got a heat sink on it which will really drop that 65C/watt number to something more normal-ish.

In short, as long as it's not shutting down, you're good. If you're still worried about it, pull down a few datasheets and have a look at a thing called an 'external pass transistor'. Basically, you use the regulator to control the base of an external transistor which bypasses just enough juice to keep the regulator working and to basically do all the work for the regulator.

If not that, go ahead and parallel a couple of 7805's. Just keep in mind that 7805-A might be set at a slightly higher voltage than 7805-B, so you need to put a small value/high wattage series resistor inline with each output, or in bad cases, you'll have to isolate each regulator's output from each other with an inline diode.

Try it out...you won't hurt anything. At worst, they'll overheat and shut themselves off until they cool off...