The FAN7930B is an active power factor correction (PFC) controller for boost PFC applications operating in critical conduction mode (CRM) mode. It uses voltage-mode PWM to compare an internal ramp signal with the output of an error amplifier to generate a MOSFET turn-off signal. Because the voltage mode CRM PFC controller does not require the rectified AC line voltage information, the power loss of the input voltage sensing network required by the current mode CRM PFC controller is saved. The FL7930B provides over-voltage protection, open-loop feedback protection, over-current protection, missing input voltage detection, and under-voltage lockout protection. An additional OVP pin can be used to shut down the boost power stage when the output voltage exceeds the OVP level due to a broken resistor connected at the INV pin. If the INV pin voltage falls below 0.45V, the operating current drops to a very low level and the FAN7930B can be disabled. By using a novel variable on-time control method, the THD is lower than conventional CRM boost PFC ICs.
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