So I've been googling what is needed to power an Arduino in a car, and there doesn't seem to be a consensus, or rather, there's many many ways to acheive it.
The pic above seems a fairly elegant solution to me, the LM2937 is designed specifically for the unique requirements of the automotive environment, but I'm unsure if it's complete enough. The tech docs for the LM2937 imply there ought to be some sort of filteringering before the regulator, as it says a 0.1uF cap should be used if the reg is more than 3" from the supply filter.
Is that 0.1uF on its own enough to filter? I have seen some mention that an inductor should also be used. I wouldn't have any idea how to sized an inductor if I needed it.
Why don't you believe the data sheet? Where did you "see some mention"? The specs only "imply" filtering? I suggest posting links to the device information.
It mentions the 0.1u cap is needed "if the regulator is located more than 3 inches from the power-supply-filter capacitors.", what I'm un sure on, is this 0.1u cap sufficient on its own as my filter, or if it's to be used in conjuntion with other components.
You can only be sure if you know what reason you are using the cap and if it makes a difference.
Yeah, that 3 inch spec is a little loose considering it could be 3 inches of anything. Generalities such as this one are based on assumption that other important standard design features are taken care of. It boils down to the actual complexity of electronics which has to consider an amazing number of limitations and properties of different devices. With power layout, the motto is "short and wide" for conductors. So, no cheating on trace size, no meandering traces and adequate interfaces to the components. Note this is usually almost the same game, regardless of analog or digital circuit. If you start looking at really good PCB layouts you will begin to just see how power integrity is guaranteed.
Also, considering the additional filtering you mentioned, would seem to ask what specifications should be met?
There are semiconductor solutions to input voltage conditioning, that would outperform a simple inductor. These shielding or protective elements also have to be laid out on the PCB with minimal ohmic connections to the common conductors. How many or how few elements you should use, depends on a trade off between cost and performance.
