I have a number of 3v arduinos from sparkfun, love them and have them deployed in all kinds of projects around the house.
However, i would like to convert most of them to LIPO power. i have worked with lipos a little, have a good charger and a fuel gauge circuit, but what (if anything at all) should i do to run my pro mini arduinos from them?
Should i use a simple 3.3v TO-220 style regulator, a more advanced power circuit, or simply hook the sucker straight up to the arduino power?
I'd run the board directly from the battery. Stable 3.3V may be hard to get from 3.7V.
Look at pololu.com regulators. One is a buck-boost regulator, will work with input that is higher or lower than the desired output. 3.3V from 4.2V down to 3.7V should be workable.
3.3V/8 MHz Arduinos will also run just fine straight from battery as DrD says. I have a 8 MHz Promini based RF remote control, I run it directly from LiPo battery, with MAX1811 chip for charge control from 5V source. Rf Transmitter works fine over the battery range also.
If you are controlling 3.3V devices, you'll probably need the regulator tho.
Hah, there is a 3.3v regulator right on there! Hook up to raw instead of vcc. Should have looked harder before posting.
For other, less forgiving items, I am considering a 1-4 to 5v booster and dropping that back to 3.3 with a regulator (which requires 1.5v over desired output) ick!
blah44:
Should have looked harder before posting.
Or "should have read better before posting".
CrossRoads gives very good advice.
Onboard lineair regulators have a dropout voltage of ~1volt
You have to put 4.3volt or more onto the raw input for 3.3volt on the micro.
Switching regulators can be more energy efficient than lineair regulators.
Read the specs. Do the calculations.
Boosting and dropping will use battery power.
This regulator has high efficiency, low quiescent current, and makes 3.3volt from 3.5 to 36volt.
Leo..