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.

Both PFC and PWM have the Green Mode Functions. When  the  load  is  below  GMth,  Green  Mode  Threshold, PFCOUT is turned off. The GMth can be  programmed by the  designer.  PWM  Green  Mode  will  happen  when  the PWMCMP (PWM Comparator) Duty Cycle is less than ~ 6%, in the next cycle, the PWMOUT pulse will be removed until PWMCMP Duty  Cycle  is greater than 6%, then the next cycle, PWMOUT pulse appears. PWM has a PWMtrifault pin  which can sense the PWM

short and determine the GMth to turn off PFC.

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Features

• Patent Filed #5,565,761, #5,747,977, #5,742,151,

  #5,804,950, #5,798,635

• 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 which can be > 2000K or higher 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

• 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

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Applications

• AC Adaptor

• Open Frame

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Packages

• 10-Pin SOIC package

　

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Datasheet PDF file 6805 / 6806 PDF