# Low Dropout Regulator Selection

Ok, I'm new to the whole electronics thing, but I am gaining a little bit of knowledge all the time.

I'm looking at putting an Arduino on a breadboard in an attempt to learn the circuit better so I can build one from scratch, just for fun and for the future development of a project I've been working on.

this is the LDO regulator that I was just looking at. Datasheets don't really make a whole lot of sense to me, so I don't know what I'm looking at/for. But I think I'm reading this correctly.

This is saying that if I want an output of 5V, I have to supply atleast 5.5V, correct? The other regulators I've briefly worked with, I remember reading or watching a video that said you had to have atleast +2 volts of input to get the 5V. So, I was under the impression that is the "dropout voltage"? I know the arduino's regulator can use a 6V input, but that it was not recommended, instead, using a 7V or higher input would provide more consistent operation. So that goes in line with the +2V difference.

I've also heard something about switching regulators and that they don't waste as much in the form of heat, that they're more effecient. My main goal with the project I'm working on is keeping the power supply at 6V and possibly using 2x 6V Lead Acid batteries in parallel to increase the length of time it can stay in the field.

Any thoughts or suggestions would be a great help.

That's the whole point of an LDO, basically as you said in order to sustain 5v you need a little extra head room normal regs require an extra couple of volts, for example a 6v lantern battery pass it through a 7805 and you will get around 4v the solution would be to use an LDO like the one from jameco.

Otherwise finding a 7v source may be tricky and most woluld supply 9v... but now we start talking about heat waste, dissipating the excess voltage to supply 5v.

A switching regulator is usally the best alternative unless you need a very clean voltage supply with as little ripple as possible.

I guess I need to look up what ripple is then. I really have no clue. So, let me read about that, and then let me get back with you.

So, I guess since my project is working with a camera, it might not be the greatest idea to even try the switching regulator. If I only have to supply 5V and a 6V battery is still .5V above the minimum required, I really shouldn't be losing too much from heat.

I think I can live with that. Thanks so much for your help.