The chip in question is likely the 3.3 volt variant of the regulator chip. Looking at the data sheet[1], it can be made variable with a voltage divider. (Provided you disconnect the rest of the circuit, of course)

The physics of step down converters are well known, they've been around for a very long time.

[1] https://web.archive.org/web/20051001031947/http://www.anachi...