CHAPTER 8 LED Drivers with Power Factor Correction 8.1 Power Factor Correction Power factor correction, or PFC, is a term used with AC mains powered circuits. A good power factor is when the AC current is in phase with the AC voltage. A pure resistive load has a power factor of 1, but active loads tend to have power factors closer to 0.5, unless special measures are taken to `correct' this. The most common power factor correction circuit is a boost converter. The AC line voltage is boosted to about 400 V and the amplitude of the current pulses into a storage capacitor is arranged to be sinusoidal. This is achieved by switching the