The FAN7930C is an active power factor correction (PFC)
controller for boost PFC applications that operate in critical
conduction mode (CRM). It uses a voltage−mode PWM that compares
an internal ramp signal with the error amplifier output to generate a
MOSFET turn−off signal. Because the voltage−mode CRM PFC
controller does not need rectified AC line voltage information, it saves
the power loss of an input voltage−sensing network necessary for a
current−mode CRM PFC controller.
FAN7930C provides over−voltage protection (OVP),
open−feedback protection, over−current protection (OCP),
input−voltage−absent detection, and under−voltage lockout protection
(UVLO). The PFC−ready pin can be used to trigger other power stages
when PFC output voltage reaches the proper level with hysteresis.
The FAN7930C can be disabled if the INV pin voltage is lower than
0.45 V and the operating current decreases to a very low level. Using a
new variable on−time control method, total harmonic distortion
(THD) is lower than in conventional CRM boost PFC ICs.