Regulate higher voltage for mcu and tracking pre-regulator

[MarkusAnd]

I am currently designing a lab bench power supply using the LT3080. The design is inspirated from Daves PSU-design series.
It will have an input of 18V and an output of 0-15V and 1A. I am going to use an Atmega328 to control the limits and a display. For that I of course need 5V and I am using a LM2576 to drop 18V to 8V and then using a LM7805 to get a steady 5V output. I also want to add a tracking pre-regulator to the LT3080 which will keep the input about 1V above the output.

Now the question is, how could I generate both the 5V and the voltage for the tracking pre-regulator while keeping the part-count low? Is there a good dual-output switcher that covers my voltages and currents, or is it better to use two individual switchers? Or is there even a better way than switchers?

I will use an ac-dc wall adapter to get the 18V DC input.

[Marco]

In theory there are single inductor multiple output buck converters and in theory you could use the atmega as the switching controller ... but just throw on two high voltage buck converters and save yourself the headache.