CM6904

GENERAL DESCRIPTION CM6903/4 Low Pin Count PFC/PWM CONTROLLER COMBO FEATURES The CM6903/4 is a space-saving PFC-PWM controller for power factor corrected, switched mode power supplies that offers very low start-up and operating currents. For the power supply less than 500Watt, its input current shaping PFC performance could be very close to CM6800 or ML4800 architecture. Power Factor Correction (PFC) offers the use of smaller, lower cost bulk capacitors, reduces power line loading and stress on the switching FETs, and results in a power supply fully compliant to IEC1000-3-2 specifications. The CM6903/4 includes circuits for the implementation of a leading edge, input current shaping technique “boost” type PFC and a trailing edge, PWM. The CM6903’s PFC and PWM operate at the same frequency, 67kHz. The PFC frequency of the CM6904 is automatically set at half that of the 134kHz PWM. This higher frequency allows the user to design with smaller PWM components while maintaining the optimum operating frequency for the PFC. An PFC OVP comparator shuts down the PFC section in the event of a sudden decrease in load. The PFC section also includes peak current limiting for enhanced system reliability. Patent Number #5,565,761, #5,747,977, #5,742,151, #5,804,950, #5,798,635 Pin to pin compatible with FAN6903/4 Enable lowest BOM for power supply with PFC Internally synchronized PFC and PWM in one IC Patented slew rate enhanced voltage error amplifier with advanced input current shaping ...