Please refer to the following table from the datasheet (Rev 0 2/15). Mode, SS, Coarse, and Fine are all analog inputs. Every resistance value corresponds to a different function or parameter.
Outputting 5V and 2.5V with 12V input is achievable. To get 5V output, COARSE should be selected as 4.756V, with a corresponding resistance of 3.01k ohm. FINE needs to be selected as 0.254V, with a corresponding resistance of 4.75k ohm. To get 2.5V output, COARSE should be selected as 2.228V, with a corresponding resistance of 24.3kohm. FINE needs to be selected as 0.272V, with a corresponding resistance of 3.01kohm. Unlike other ICs, resistor programming is used for Mode selection. For a 12V input, dual output, we can choose a 200k ohm for MODE, PHASE SHIFT, AND FSW which will correspond to two signel-phase independent outputs, 180 degree phase shift, and 1MHz switching frequency.