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UCC28881: How to choose the AC/DC converter to support PSR/SSR structure

Part Number: UCC28881
Other Parts Discussed in Thread: UCC28704, UCC28740, , UCC28711

Hello TIer,

as I know the PSR(primary side regulation) structure use VS pin of controller to sampling aux winding voltage. UCC28704

May I know FB pin of controller can use for PSR structure? UCC28740, UCC28881

Is there any other way to achieve PSR structure in general controller? or what functions the controller must have.

  • Hello,

    Please see my comments below.

    as I know the PSR(primary side regulation) structure use VS pin of controller to sampling aux winding voltage. UCC28704

    May I know FB pin of controller can use for PSR structure? UCC28740, UCC28881

    The UCC28740 makes adjustment to frequency and peak current based on FB current.  Please see figure 15 from the data sheet below.

    Is there any other way to achieve PSR structure in general controller? or what functions the controller must have.

    >See above; as well as figure 15 from the data sheet.

    The UCC28881 uses on off control.  When the FB pin is below 1 V it delivers 62 kHz switching packets.  When it is below 1V the gate drive is off.  Please see below.

    Regards,

  • Dear Sir,

    thanks for your advise. may I know the UCC28740 and UCC28881 can support for PSR?why?

  • Hello,

    The UCC28740 and UCC28881 were not designed for PSR control.  The UCC28740 control law is similar to the UCC28711 PSR controller.  If you want to do primary side control, I would recommend using the UCC28711 over the UCC28740 and UCC28881.

    Regards,