A series pass circuit conducts a pass current between a first side and a second side. A power source is coupled to the first side, while a capacitor is coupled to the second side. A system component whose power supply input is coupled to the capacitor may exhibit pulse-type activity. A control circuit increases the resistance to the pass current, in the series pass circuit, in accordance with a reporting signal that indicates whenever the system component is more active or less active. Other embodiments are also described and claimed.