The FAN6961 is an 8-pin, boundary-mode, PFC controller IC intended for controlling PFC preregulators. The FAN6961 provides a controlled on-time to regulate the output DC voltage and achieve natural power factor correction. The maximum on-time of the external switch is programmable to ensure safe operation during AC brownouts. An innovative multivector error amplifier is built in to provide rapid transient response and precise output voltage clamping. A builtin circuit disables the controller if the output feedback loop is opened. The start-up current is lower than 20A and the operating current has been reduced to under 6mA. The supply voltage can be up to 25V, maximizing application flexibility.