John, it's a 100 ma regulator which only has to power processor. The processor can take 40 ma max per pin, normally 20 ma but the board can only handle 200 ma maxed out. Hence the Darlington. The Array can handle 500 ma per pin max.
Mind you I could've used MosFets but don't need 10 amps per channel unless I was using car headlight bulbs for lights.. :lol: