# Can you source a single circuit with 2+ digital pins for higher current needs?

I apologize if this is an utterly stupid question, but I would rather be told I'm an idiot than burn up an Arduino board.

I have an Uno Revision 3. I understand that each digital I/O pin can source/sink a maximum of 40mA, and each Vcc can source a maximum of 200mA total. At 5V, the maximum power per pin is then 200mW. My question is this: If a given circuit setup demands greater than 200mW power, i.e., greater than 40mA current to fully power all components, can the circuit be effectively/safely powered by two+ digital I/O pins set to OUTPUT, HIGH and an equal number of pins set to OUTPUT, LOW?

To clarify, say we wire up a circuit on a breadboard that requires 250mW (5Vx50mA) to operate, which if sourced by a single pin would lead to damage. If we connect digital pins 12-13 to the (+) breadboard power rail and set them to OUTPUT, HIGH and connect pins 10-11 as grounds to the (-) power rail set to OUTPUT, LOW, would we then be able to operate the circuit without damage to the components/board?

I know that the above proposed setup works for batteries in parallel, but as one contributor mentioned, power supplies are not batteries, primarily due to common ground conflicts. I've found tons of information on the limits of sourcing many independent circuits with digital pins, but nothing about sourcing a single circuit with more than one pin. Any insight on this topic would be greatly appreciated.

In theory yes but in practice don't. You have to switch the pins at exactly the same time so that means you can't use digitalWrite but you have to use direct port manipulation.
Do it right use a transistor.

This parallel arrangement does not work for batteries because they cross charge and that damages them.