[RyanN]

Originally Posted by Al Skierkiewicz

A 78XX regulator reuires a minimum of 2 volts across the device for operation. If you feed the regulator with 5 volts, the output will be 2 volts below that which is not enough for the devices to reliably operate and my be so low as to trigger the power function of the controller. The 7 volt minimum satisfies the 5 volt regulator and it is designed to work up to a fifteen volt input. So the specs have more to do with the 7805 then with the operation of the board itself. Although you could run it off a PWM the power there is coming from the 7.2 volts backup battery. I would go as recommended, attach to a breaker and the main power, +12.

I would definitely use 12V. If you use the 7.2V backup battery, you are only giving yourself a leeway of 1/5 of a volt (our backup battery was dead... around 6.5V). I believe under-volting the IR board can cause it to fail, as was in our case. The programming within our PIC controller failed. If you put it on a 12V circuit, you give it a 5V leeway, which is pretty good.