An integrated circuit includes both ballast control and driver circuitry and power factor correction (PFC) control circuitry. At the beginning of preheating, power is provided to the load circuit at a voltage below a voltage at which the lamp can ignite, and the PFC control circuitry can then bring the DC bus voltage up to its running value. For this purpose, the PFC circuitry is enabled depending on the mode of the ballast control and driver circuitry. The DC bus voltage is regulated at a lower loop speed when the lamp is running than when the lamp is ramping to ignition, to alleviate DC bus drop. A criterion is applied to determine whether over-current detect signals indicate an actual fault. For this purpose, detect signals during ignition ramping can be counted and compared with a fault number. Through comparing the detecting voltage and the upper and lower window voltage, the service life terminating condition of the lamp can be detected. When the lamp is close for a short time, the lamp can fast restart without completely preheating.