Throughout the past few months, I have done a number of microcontroller projects. One of the things I have always dismissed is the possible effects of linear regulator "heat". I was wondering from some of you experts, if this is typical or something I am possibly doing wrong.

Just as an example, my current project uses an LP2985 5v regulator, which is a very tiny sot 5 pin device (slightly larger than a sot23) that is designed for low power products. According to the datasheet these things can source quite a bit of current (300mA comes to mind). In my application, my circuit demands at times around 60-80mA. This produces some heat. I'd describe it as too hot to touch for a few seconds at a time, but not "blister" hot. This little regulator doesn't have any backplane that could be used to, say heatsink to the board's copper.

Is this damaging to the part or is this normal? And when does it become not normal? I can only imagine how much heat is produced regulating 5 volts at 300mA.

Are there any general rules about this? Things I should watch out for?

I thank everyone for all of the help in advance. This, thus far has been a great board in which I have learned so many things about electronics in general and the 8051 parts.

James