Does anyone know why two DC-DC converters are used to make 5V from Vin on the Arduino UNO? I've seen another thread that said it was an "alternate parts" selection (not clear from the schematic), but Vin (which is the net straight after D1) is on two devices. One is clearly the MC33269 LDO in the ST package, but the other is an 8 pin device labeled 103. Is that really a second regulator (the MC33269 in the D package)? What is the point?
You mean the 3.3V reg?