GENERAL DESCRIPTION

The CM6805A and CM6806A are the Green-Mode PFC/PWM Combo controller for High Density AC Adapter. For the power supply, its input current shaping PFC performance could be very close to the performance of the CM6800 or ML4800 leading edge modulation average current topology.

CM6805A/CM6806A 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 / CM6806A includes circuits for the implementation of a leading edge, input current shaping technique “boost” type PFC and a trailing edge, 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.

FEATURES

♦ Both PFC and PWM have the Green Mode to meet blue angel and energy star spec.

♦ 10-Pin SOIC package

♦ PWM pulse skipping for the green mode

♦ Use RAC as the Startup resistor around 5 Mega Ohm at IAC pin

♦ It can use the HV bipolar to start up the chip and it helps green mode.

♦ Easy to configure into Boost Follower

♦ 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 technique

♦ Universal Line Input Voltage

♦ CCM boost or DCM boost with leading edge modulation PFC using Input Current Shaping Technique

♦ Feedforward IAC pin to do the automatic slope compensation

♦ PFCOVP, VCCOVP, Precision -1V PFC ILIMIT, PFC Tri-Fault Detect comparator to meet UL1950

♦ Low supply currents; start-up: 100uA typical, operating current: 2mA typical.

♦ 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

♦ VINOK Comparator to guarantee to enable PWM when PFC reach steady state

♦ High efficiency trailing-edge current mode PWM

♦ Exact 50% PWM maximum duty cycle

♦ UVLO, REFOK, and brownout protection

♦ Digital PFC and PWM soft start, ~10mS

♦ Precision PWM 1.5V current limit for current mode operation

♦ PWMtrifault to sense DC to DC short and Turn off PFC at GMth

♦ PWMtrifault also can be programmed to do the Thermal Protection

APPLICATIONS

♦ AC Adaptor

♦ Open Frame