Using boards like the Uno and a MiniPro(5v), I've successfully done some analog sensor reading. Most of my sensors require an accurate 5v excitation voltage, so I just use Vcc on the 5v arduino boards. But now I'm trying to use these same sensor but on some 3.3v boards (Fio, JeeNode).
I tried using a Pololu 5v boost regulator (http://www.solarbotics.com/products/19210/
) but it's too noisy and causes about 5 bits of fluctuations on the ADC sample of the sensor readings. Even with the sensors removed, I sampled the output of the boost regulator (through a resistor divider), and it still shows several bits of noise.
Looking at spec sheets, it seems like most boost regulators have a fairly large (at least ~2%) error on the output voltage, so I thought about a precision voltage reference, which can get down to 0.5% and even 0.1% error, but all seem to require more than 5v input.
What's the easiest and most accurate way to provide a precise 5v reference from a 3.3v board?