I am working on a small portable device which I will power from 3 AAA cells. I want maximum battery life, and I have picked many of the chips involved for that purpose.
The nature of this circuit is that I will use a very low power timer (PCF8593) to interrupt a Nano from sleep mode now and then, so the Nano will be in very low power mode most of the time. But what about the little power LED on the Nano? Does it go out when the chip is in sleep mode? I suppose if I am very careful, I can disable it without ruining the board, but better if it just goes out in sleep mode.
The power LED will stay on in sleep mode. You could save some current by removing it. I did the same on one project and it made a difference. If maximum battery life is of utmost importance then the Nano isn't the best choice I'm afraid. But if you're going to use a Nano removing that LED will help.
jrdoner:
I would be interested in hearing from you as to what better choice I could make. the 328 is plenty big for the code I need.
The problem is not the 328p. You could use an attiny, but that doesn't save much.
The real problems are that the nano has a power light, a usb interface chip, and a third rate regulator.
A pro mini (which has no usb serial interface on board - instead you use external adapter with the ftdi pinout) with the led and regulator removed is a lot better.