Moteino resetting

[tleavitt]

The reason the SOT223 package is better thermally is that it has a thick copper tab that gets connected to an even larger copper plane on the PCB.  The Moteino doesn't have this copper plane for the VR connection.

If you look at high powered devices such as ESP8266 modules, you will see a large SOT223 VR in that package, but those are energy hogs.  The Moteino board was designed to operate in energy efficient projects and normally doesn't required that extra bulk or wasted power.

A linear regulator in that environment would operate at about 20% efficiency.  It might be cooler than a different solution, but it certainly wouldn't be efficient.  Think of as covering 80% of your solar panel with electrical tape.

I dont mean put the SOT-223 MCP1703 on the moteino itself. I have a PCB board beneath it that the moteino plugs into, and that board gives me room to mount resistors, diodes, and some screw terminals. I would attach the larger 1703 to that board and if necessary, there are heatsinks out there that can fit over the SOT-223 package.
I dont see why the SOT-223 MCP1703 would be any less efficient than the SOT-23A MCP1703 mounted on the moteino itself. Its the same chip just packaged differently. And after mulling it over, what I would do is get a 5V MCP1703 to handle 12V input and that would feed the VIN pin on the moteino. That way the moteino's regulator can operate efficiently while the larger 5V regulator on the baseboard handles dropping the bulk of the voltage and dissipating the heat generated from that. And by my calculations, the 5V regulator should be able to handle 207mA and the 3.3V should be able to handle 157mA in our 90* weather here.