The voltage seen on the capacitors is related to the power supply voltage, PDD.
CP1 = 1.5*PDD; CP2 = PDD/2; CP3 = PDD; CP4 = 3*PDD CP5 = 4*PDD
So for example, if PDD = 5V then:
CP1 = 7.5V; CP2 = 2.5V; CP3 = 5V; CP4 = 15V; CP5 = 20V
These are nominal values, it is prudent to leave some margin for selecting rated capacitor voltage. A factor of 2x is recommended.