PFC-PWM Controller Provides High Efficiency in Dual-Switch Flyback Topologies
Mon, 12/20/2010 - 12:05pm
Fairchild Semiconductor’s FAN6920MR combines a power factor correction (PFC) controller and a quasi-resonant PWM controller. For PFC, the device uses a controlled on-time technique to provide a regulated DC output voltage and to perform natural power factor correction. With its total harmonic distortion (THD) optimizer, this controller can reduce input current distortion at zero-crossing duration to improve THD performance, according to the company. For PWM control, the FAN6920MR provides several functions to enhance the power system performance including extended valley detect up to the 12th valley cycle for reduced switching frequency, improved light load efficiency, green-mode operation, an internal 10 ms soft start and high/low line over-power compensation. Additionally, the device provides many protection functions including brownout, secondary-side open-loop and over-current with auto recovery, external auto-recovery protection triggering and internal over-temperature shutdown.