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PFC Circuit Description As explained earlier, the inductor current in the boost PFC is in CCM. The CCM operation results in lower peak and RMS currents compared to Critical Conduction Mode (CrM). The CrM operation brings in a number of other benefits but is typically employed at lower power levels. The CCM operation greatly simplifies the design of the boost inductor and reduces the stress on the boost FET and boost diode. Also, the CCM boost works in fixed frequency simplifying the EMI filter design. NCP1654 is a simplified CCM boost PFC converter in an 8-pin package that minimizes the number of external components. Figure 3 below show a typical application circuit of the NCP1654 based PFC [1]. Salient features NCP1654 provides are mentioned below: 1. Programmable Overcurrent Protection 2. Brownout Detection 3. Overvoltage Protection 4. Soft Start 5. Continuous Conduction Mode 6. Average Current-Mode or Peak Current-Mode Operation 7. Programmable Overpower Limitation 8. Under voltage Detection for Open Loop Detection (shutdown) 9. Inrush Currents Detection