Newer generation controllers like the ICE1PCS01 and the ICE2PCS01 rely on a different control technique, called single cycle control. They do not require input voltage sensing instead they control the off time to regulate input current draw indirectly. The net control function is the same but with fewer IC pins required. It is worthwhile to note that with lower input voltages, such as PFC for the line voltage standard for domestic and office use in the USA, the MOSFET switch duty cycle tends to be fairly high over the AC waveform due to the high voltage step up required which is approximately 400 V.  This has the correlating effect of having a rather narrow duty cycle for the diode energy transfer, which raises the performance requirements for the boost diode in CCM PFC at low line. This topic will be discussed more later in this presentation, and quantified in detail.