I'm having this project now. My DC-DC switched capacitor is followed by the LDO for regulations. I had observed that the line and load regulations are doing well.
My question now, is what other criteria that I need to looked into aside from the two regulations.
The PSRR at switching frequency and its first few harmonics
is the big deal as far as noise goes. Many PMOS LDOs have
poor HF PSRR, since they have a lot of through-capacitance.
So you will need a very stiff output capacitor to divide that
away, and many LDOs don't like super low ESR caps on the
output.