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UCC28070: UCC28070

anjana desai
Prodigy 190 points
Part Number: UCC28070

In the schematic of 300W PF circuit, schematic shows only two Switching mosfet used in boost converter. But in 1.2KW schematics PR779 shows 4 mosfet (Q3, Q4, Q5, Q6) for boosting. My doubt is why these two additional mosfets are used here? are they to increase the power rating of PFC circuit? If yes then while using UCC28070 IC how to calculate no of mosfets required to achieve the power rating?

 Also what is the switching frequency used for 1.2KW PFC?

  • 0
    TI__Mastermind 34465 points
    Hello anjana desai,
    You are correct in your assumption that the PR779 reference design uses 2 parallel FETs in order to handle the extra power associated with a 1.2kW application.
    If you use the Excel calculator tool for the UCC28070 you will be able to check the rms and peak current for the FETs.
    With this information and the RDS(on) you can calculate the power dissipation in the FETs.
    Obviously RDS(on) can be lowered by paralleling FETs.
    It is possible to parallel up to 3 FETs if the application requires it.

    The switching frequency for this reference design is set at about 175kHz
    Regards
    John