A Multiplier Based Control Of Pfc Chip Design

Switching power supply has the advantages of wide input voltage range，highefficiency，high power density，small size and light weight, ect. Complies with thedirection and trend of development of electronic equipments, Therefore, gets extensiveresearch and considerable development. But, it’s disadvantages gradually appear withthe large number of applications, tha’s supply the back-level circuits by filtering directlyafter rectifier, this way will make the input current distort badly, and then make the netemerge harmonic pollution. And power factor correct technology is the most effectiveway to solve the harmonic pollution by now. With the continuous development ofpower electronic devices, Research and application of power factor correction （PFC）technology continues to heat up.This paper designs a PFC IC which based on Multiplier Control, and simulatesthe IC application solutions in order to verify the IC’s overall performance. The thesismainly completes the following work:Firstly, introduces the basis of switching power supply and also analyses anddeduces the basic theory of switching power supply and then gets the DC transferfunction of switching power supply basic topology, still analyses the wave form ofinductor’s current, then gets the way to determine the worst input voltage of basictopology and to design the basic component inductor under wide input voltage range.Secondly, still states the principle of power factor correction technology whichbased on Multiplier Control, in order to facilitate the follow-up design of the modulesinside IC and its application circuit.The main part of the paper is principle analysis,circuit design and simulation verification of main function modules inside IC. The mainmodules include under voltage lock out circuit（UVLO）, bandgap reference voltagesource, RC oscillator, voltage error amplifier, multiplier, current error amplifier, PFCcomparator.Finally, simulates and analyses the IC’s total function and parameters based onCSMC0.5um BCD process. Application requirements: wide input voltagerange（80²60V AC）, the output voltage isV_OUTDC=380V and also the ripple voltage is less than3.5%, the maximun output power isP_OMAX=300W, total current harmonicdistortion（THD） is less than8%, and also choices and calculates the components ofexternal circuits under these application requirements, simulates the whole circuits so asto verify the correctness of the design at last. The simulation results show: when inputvoltage is220V AC and the output power is300W, THD is7.9%, PF is99.7%, theefficiency is92%and output ripple voltage is3.2%, meets the design requirements andalso verifies the correctness of the design.