Converting Mega to work at 3v3 from a 3.7v LiPo

Projects General Guidance
1

I'd like to power a Mega 2560 R3 with a 1S 3.7V LiPo battery pack as well as have 3v3 instead of 5v on the pins. Am I correct in thinking that this will require:

  • Replace 5v LDO with 3v3 version
  • Remove 3v3 regulator and jump input which is now 3v3 to output.
  • Remove USB fuse and jump USB 5V to 3v3 LDO input with a diode.
  • Replace input protection diode D1 with a jumper to eliminate voltage drop.
  • Reduce clock speed from 16 MHz to 8MHz

Did I miss anything?

2

That looks like a lot of work. How good are you at desoldering the clock crystal?

A 5v boost converter is very efficient and not expensive to buy.

3

Make/get hold of a bootloader suitable for 8Mhz...

But like Morgan said, a 5v boost converter is a hole lot easier....

4

Mega R3 uses Atmega2560, needs 4.5V to work correctly.
You need Atmega2560V to work at lower voltages.

ATmega2560/ATmega2561:

• 0 - 16MHz @ 4.5V - 5.5V

ATmega2560V/ATmega2561V:

• 0 - 2MHz @ 1.8V - 5.5V, 0 - 8MHz @ 2.7V - 5.5V

5

Found the Sparkfun Arduino Mega Pro 3.3v which uses the atmega 2560V.

6

There you go then. From the comments, looks like it's been around for a while. 4 in stock, buy one quick!

7

Looks like the sparkfun mega is 4 boards abay from being a retired product.

Adafruit has this guide to converting an arduino to 3v3. Wonder if it's worth a try.