I was wondering if there are any good IC's available for doing this. I have been thinking up some ways to do it, however, I am sure there are most efficient methods. I am not too well versed with all the different types of integrated circuits and their differences, so I was hoping to get some guidance on this. I plan to use 4 AA batteries with a 5V buck/boost voltage regulator to get a steady 5V rail. I need, however, both 5V and -19V to -21V for the device I am making. Would anyone be able to help me with how to generate the negative rail?
My main constraints are size and cost, however, I would love it to be as efficient as possible to prolong battery life.