A charge pump generator system and method is provided which more precisely maintains the level of an internally generated voltage supply by operating some or all of the available charge pumps depending upon the voltage level reached by the voltage supply. When the voltage supply is far from its target level, a first group and a second group of charge pumps are operated. The first group may preferably have a faster pumping rate or a greater number of charge pumps than the second group. When the voltage supply exceeds a first predetermined level, the first group of charge pumps is switched off while the second group remains on, such that the rate of charge transfer slows. The second group continues operating until a second, e.g. target, voltage level is exceeded. The slower rate of charge transfer then effective reduces overshoot, ringing and noise coupled onto the voltage supply line. Preferably, at least one charge pump operates in both standby and active modes, thereby reducing chip area.