This chart summarizes the key differences and impact on the design. Due to high peak currents, CrCM mode and DCM mode require a larger EMI filter for the same power level. The input rectifier requirements for either PFC mode are less costly than for capacitor input filters, as the peak currents are lower. The input capacitor must be a small X series film capacitor with low ESR and low ESL. The boost MOSFET for the DCM/CrCM PFC should emphasize high peak current and low turn-off losses. For the CCM mode, peak currents are lower for the same power but turn-on losses as well as turn-off losses must be optimized. The CrCM converter can use a relatively slow conventional diode, though performance improvements with overload sometimes show benefit with a fast diode. Unlike the CCM mode PFC, ultra fast diodes are not needed. The output capacitor in both cases has some significant demands with regards to ripple current. Hold up time may be the governing criteria for either application, along with ripple current at high temperature which is a function of ESR.