Bipolar power diodes for Switch Mode Power Supply Understanding PFC - SMPS applications What is Power Factor Correction (PFC) PFC bene?ts ? It can be de? ned as the reduction of the harmonic content, and / or the aligning of the phase angle of incoming current ? PFC is required to reduce disturbance on the AC distribution net and maximize the real power drawn by the power supply from the AC line. ? Fully compliant with regional regulations imposing restrictions on power factor and total harmonic distortion (THD) in high-power applications (>75W), including: - CCC or ‘3’C in China - IEC1000-3-2/EN61000-3-2 in Europe - ‘80plus policy’ in America Boost PFC circuit - JICC61000-3-2 in Japan ? Meets energy saving and ‘green energy’ trends to reduce electricity costs D + ? Optimizes and improves circuit performance - reduces mains harmonic content - decreases peak current at mains frequency - minimizes the electrolytic bulk capacitor used at PFC stage output ~ V IN ~ - + VOUT - bra785 - shrinks mains transformer size and weight - improves output regulation of downstream DC/DC converters Bipolar-power diodes in various SMPS application Computer: desktop Computer: ?le server 1. PFC diode 3. output rectifier forward 1. PFC diode 3. output rectifier forward PFC for Pout > 70 W 3.3 V 5 V 3.3 V 20 to 40 A PWM PWM standby 5 V 20 to 40 A 3.3 V 5 V 3. output rectifier 5 V -5 V 12 V -12 V 12 V 10 to 20 A -5 V 2. snubber diode -12 V 2. snubber diode bra787 3. output rectifier bra788 Computer and consumer adaptor Consumer: TV display 1. PFC diod