Buck boost led driver

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Hi, I need a design for a led driver with 28W @ 350 mA, 82V output but it should be adaptable to provide from 24W to 33W. It seems to me that the Buck-Boost topology with an LNK409EG or LNK419EG is the most simple and economical. I've tried the PIXls Designer (Release 8.6.0.2) but for the LinkSwitch-PH the only option is the Buck topology. Could you please help me with a design spreadsheet, schematic, etc..?

Thanks in advance and best regards!

Paulo

In the PIXls designer, please choose "LinkSwitch-PH" option. This is by default based on flyback topology, but if you want to use it as buck-boost, please set VOR = VO.
For additional info, please check DER285 as well which I found to be close to your requirements, if you wish to use buck-boost.

Thanks for your comments. In the DER-285 I think I should ignore the Transform Secondary Design Parameters section, right?

In DER-285 schematic diagram: wich resistors correspond to RV1, RV2, FB pin resistor Upper V pin resistor and LowerV pin resistor? (Just for the sake of not misreading!)

Regards,

Paulo

Please ignore the transformer secondary design parameters.

RV1 is the upper Vpin resistor, which corresponds to R3 (2Meg) and R4 (2Meg) on DER-285. There is no RV2 on the design.

For FB pin current, please refer to DER-285 p.11 (Circuit Description)

OK! Thanks a lot!!!