I've been making plans for my first Arduino project, and am currently thinking about how I want to do the power supply. This project is going to be for home monitoring (temperature, humidity, leak, smoke, etc.) so it needs to be robust and not dependent on utility voltage being present. To that end, I'm planning on a setup where I have a 15v torroidal transformer (and appropriate rectifier, etc.) providing power to a picoUPS-120. This way I will be able to have the system maintain a 12v SLA battery, and switch over to it automatically should the power fail.
From the picoUPS (which provides 12v output,) I want to build a second regulator board to very tightly control the voltages going to the arduino, sensors, etc. since I don't want bad power to fry my investment. I want this board to provide regulated 12v, 5v, and 3v3 outputs. I had been planning on using like a TI LM2576 to do the power regulation, but found that it has a dropout voltage of around 1.5v, which would mean that the regulator wouldn't work for the 12v line.
My question is - is there any way that I could safely regulate the incoming 12v power, while using the power supply setup I've been designing? I know that I could use zeners, but I was hoping for something that was more sophisticated than just a siphon for higher voltages.
Thanks in advance!