Arduino PRO power supply


I'm currently doing an autonomous power supply for a small project with an Arduino PRO 5V 16Mhz and sensors. I'm doing it with a solar pannel (10W), a "home made" charge regulator, and a 12V lead acid battery. My charge circuit is quite done.

The Arduino PRO works almost as the Arduino UNO.

My issue : as every battery, when fully charged, a lead acid haven't 12V, but almost 13.8V.

Apparently the voltage regulation is done from a MIC5205 controller. And the Arduino website advises an input voltage between 5 & 12V.

So, do you think that I should use a regulator before my micro-controller, as a LM7808 for a proper 8V ?

Or can I add, and that for the protection also a diode to protect my battery, and the Vdrop will be 0.7V isn't it ?

Thank you for your help !!!

Depending on the current drawn, the onboard regulator might get hot. To answer your question we really need to know the current drawn by your system (the sensors etc.).

If the project allowed for sleeping time (eg. if you need to sense things every minute) then that would give the regulator time to cool down. It won't get hot with virtually no power going through it.

Thank you for your reply.

I'm not drawing much, maximum 150mA under 5V, and the average is probably 100mA. But except for the night, it's drawing permanently.

All my sensors are drawing 25-30mA (5V). My Arduino Pro 20-25mA (5V), and I register values on a SD card (5-10mA) a GPS module 20-25mA (5V) and a RTC (almost nothing).

150 mA seems to be at the higher end of the range for that voltage regulator.

Try reading this:

Or as a last resort you could read the data sheet… and you would have the answers to both questions in under two minutes… about the time since I read your question to now.
The datasheet is attached.


MIC5205.pdf (829 KB)