sainohio:
This is suppose to be a low power device.
It's capable of low power operation, but that isn't necessarily going to be the primary consideration in all use cases.
sainohio:
Are you saying that it will draw no more current at 20 volts than it will at 5 volts?
There's a cool chart on the first page of the MPM3610 datasheet:
So you can see the answer is "it depends". There is a range of conditions where it will actually be more efficient with a 19 V supply (<80 mA load current) or a 12 V supply (<65 mA) than a 5 V supply. A low power device will likely be in that load current range almost all the time. You may be used to a different situation with the traditional Arduino boards that use a linear voltage regulator.