A good filament preheat is essential to meet ten thousand or more on/off cycles. All NXP Tube Lamp (TL) and Compact Fluorescent Lamp (CFL) ICs preheat the filament without the use of a PTC component. PTC resistors which are used in discrete ballasts continue to consume power during the normal operating state. NXP ballast controllers are also designed to increase the operating frequency if the mains voltage increases above its nominal value, as indicated by the green line in the chart. This increases the lifetime of the lamp compared to a discrete solution.