Using mini as voltage regulator?

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi all,

I have used a Arduino mini powered with 5 AAA batteries (7.1V) in combination with a Devantech LCD03. The Arduino is powering the LCD through the 5V and GROUND pins. My mini broke down yesterday. Could it be that the power consumption of the LCD is to much for the Arduino mini to provide? (280 mA by 5V) Would it be better to use a nano or even a separate regulator?

Best, Hans.

2

I thought that the arduino's have a max power out of 20 mA, so 280 mA is totally out of question... use a transistor instead?

3

I think 20mA is for the digital pins when you use them as ouputs. I am talking about the 5V and Ground pins.

I had the board running with the LCD for two months (about 80 hours of operation) so 280 mA might be to much but not way to much....

Furthermore I think each of the Arduino boards is different is it not?

Best, Hans.

4

My mini broke down yesterday

The key here is to investigate what broke. Is your mini still working with USB power? Will it still work if not powering your LCD?

Too much power would only break the regulator and not the processor chip.

There are many things that could be wrong apart from the regulator.
It could be the crystal or processor chip.
If it is the processor chip that went then it is likely something else broke it rather than the excess power, like a static discharge. It could even be that something has corrupted the boot loaderand it just needs re flashing.

5

Hi Mike,

Thanks.

I already thought that it was the regulator. When powering the mini I don't see 5V on the output pins but something like 0,3V. Is the regulator easy replaceable? And are there regulators on the market that could handle a bigger current and that would also fit on a mini?

Best, Hans.

6

And are there regulators on the market that could handle a bigger current

Plenty

nd that would also fit on a mini?

Don't know. Anyway it's not just the power but power dissipation, that is how hot the package gets. You can have a 1A regulator but it will only take 1A if you keep the package down to 60C.

Anyway the fact you have 0.3v on the output of the regulator could be that something is taking a lot of current. The way to be sure it is the regulator is to lift the +ve leg so it is not connected to anything and measure it again. If it still shows 0.3v then it is toast otherwise it could be the chip.

7

Hi all,

Solved my problem by not using the on board regulator anymore but an external LM7805. I connected the output of the LM7805 to the +5V and ground pins and it works flawless. With the same regulator I also power my LCD.

Thanks for the suggestions.

Hans.

8

you probably need a heat sink on the regulator. Either the new one or the one on the board you can replace. Even a piece of aluminum from a soda can would work and if the regulator was horizontal then it's even more important since the metal part is what dissipates the heat and that is usually down on the board and trapping heat.