I have a standalone atmega328p connected to a wallwart through a 7805 voltage regulator. The atmega is directly powering 6 20mA LEDs and nothing else, just reading a trimmer. I have it plugged into a remote wall socket to directly cut the power and I noticed it take about a second for the wallwart to discharge and turn off the atmega. I assume the current is slowly decreasing in this time. Is this bad for it? Is there anything I should do to improve it?
Thanks
just reading a trimmer.
A what?
I have it plugged into a remote wall socket to directly cut the power and I noticed it take about a second for the wallwart to discharge and turn off the atmega.
if the wallwart has capacitors that charge up, to even out voltage spikes, this is possible. One second is a long time, though.
I assume the current is slowly decreasing in this time. Is this bad for it?
In this case, it is a pronoun with no referent. Back to English 101, for you.
Are you referring to the Arduino (no, it's fine), or the wallwart (it's likely fine, too)?
A what?
One second is a long time, though.
Yep. I'd say at the very least 2/3 of a second.
Are you referring to the Arduino (no, it's fine), or the wallwart (it's likely fine, too)?
I was referring to the ATmega328, as the subject line reads. So if it(the atmega) is ok then thats good news. Thanks. 
A trimmer
Trimmers can be variable resistors (potentiometers), variable capacitors, trimmable inductors.
So, which is it? Precision in terminology is important.
A pot. Does that affect your answer?
Gradual drop in supply voltage will trigger the brown-out circuit at some point, so shouldn't matter. If you were driving power MOSFETS you could have an issue with them hanging around in linear region for too long, but just a few LEDs shouldn't matter.
Excellent, thank you