Powering ATmega328 without voltage regulator?

Other Hardware 3rd Party Boards
1

As I've been Google searching and reviewing various projects where the '328 is being used on a breadboard or standalone on solderboard, I've come across a couple of designs that do not use a voltage regulator like the L7805:

The datasheet for the '328 indicates 1.8-5.5V for operating voltage. Is it safe/practical to run a 5V power supply directly onto the project board without a L7805?

Saving on the cost of installing the regulator and some caps is not at issue for me, but for a small project the space savings may be desirable.

Thanks,
Jake

2

Is it safe/practical to run a 5V power supply directly onto the project board without a L7805?

Yes I do it all the time as I have several regulated 5V supplies.

3

Its fine as long as the power supply is regulated.

4

TCWORLD:
Its fine as long as the power supply is regulated.

Heck, the power doesn't even have to be regulated. It just has to be fairly steady and in the acceptable range. You can use three AA batteries (about 4.5V).

Note: if you use a voltage below 3.8V you should switch to a lower clock speed (8 MHz rather than 16 MHz).

5

Low power systems operated from batteries usually dispense with a regulator, it can take more power than the MCU.