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General
Description
The CM6805A is the Green-Mode PFC/PWM Combo controller for Desktop PC and High Density AC Adapter. For the power supply, it’s input current shaping PFC performance could be very close to the performance of the CM6800 or ML4800 leading edge modulation average current topology. CM6805A 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 CM6805A includes circuits for the implementation of a leading edge modulation, input current shaping technique “boost” type PFC and a trailing edge modulation current, PWM. The CM6805A’s PFC and PWM operate at the same frequency, 67.5kHz. A 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. PFC has a PFCOFFB pin which can use for AC brown out application and determine the GMth to turn off PFC.
u 10-Pin SOIC package. u Use RAC around 4~8 Mega Ohm at IAC pin. u Easy to configure into Boost Follower. u Enable lowest BOM for power supply with PFC. u Internally synchronized PFC and PWM in one IC. u Patented slew rate enhanced voltage error amplifier with advanced input current shaping technique. u Universal Line Input Voltage u CCM boost or DCM boost with leading edge modulation PFC using Input Current Shaping Technique. u Feed forward IAC pin to do the automatic slope compensation. u PFCOVP, Precision -1V PFC ILIMIT, PFC Tri-Fault Detect comparator to meet UL1950 u Low supply currents; start-up: 100uA typical, operating current: 2mA typical. u Synchronized leading PFC and trailing edge modulation PWM to reduce ripple current in the storage capacitor between the PFC and PWM sections and to reduce switching noise in the system u VIN-OK Comparator to guarantee to enable PWM when PFC reach steady state u High efficiency trailing-edge current mode PWM u Exact 50% PWM maximum duty cycle u UVLO, REFOK, and brownout protection u Digital PFC and PWM soft start, ~10mS u Precision PWM 1.5V current limit for current mode operation u PFCOFFB pin to sense light load to turn off PFC or PFCOFFB pin to sense Input voltage as AC Brown Out ---------------------------------------------------------------------------------------------------------------------------------------------
AC Adaptor --------------------------------------------------------------------------------------------------------------------------------------------- |
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