Get an MP1584. It is adjustable. Set it to 7V. There is really no advantage in supplying 9V. It will just be dissipated as heat. It will not give you any more reserves anywhere. You could also go directly down to 5V and skip the LDO on the Arduino.
Get an MP1584. It is adjustable. Set it to 7V. There is really no advantage in supplying 9V. It will just be dissipated as heat. It will not give you any more reserves anywhere. You could also go directly down to 5V and skip the LDO on the Arduino.