UCC28056: supply voltage for PFC UCC28056

Lillian Liu(SH)

Part Number: UCC28056
Other Parts Discussed in Thread: UCC28740,

Hi team，

Right now we use PFC controller and Flyback (UCC28740 and 28056 ) as the power supply solution.

So what is the recommended supply voltage for PFC UCC28056? Can UCC28056 use the same Vs as UCC28740 (That will decide whether the UCC28740 customized transformer auxiliary winding can supply both)

Thanks

Lillian

1 month ago

0 Mike O' 1 month ago

TI__Guru 66135 points

Hello,

Your inquiry has been received and is under review.

Regards,

0 Mike O' 1 month ago in reply to Mike O'

TI__Guru 66135 points

Hello,

Do you mean the same bias voltage? VS is actually the aux winding sensing pin.

Regards,

0 Mike O' 1 month ago in reply to Mike O'

TI__Guru 66135 points

Hello,

You may be able to use the aux winding supply to power the UCC28056. Just make sure the voltage is less than the max VCC voltage of the UCC28056 and above the UVLO threshold. You still will need a trickle charge resistor to start the UCC28056.

Regards,

0 Peter Repka 1 month ago

Prodigy 210 points

The "old school" approch was to add an auxilliary winding to the boost inductor to provide a bootstrap supply to power the controller. Whomever designed the boost inductor can add the appropriate number to turns to provide the nominal supply voltage to keep the chip powered once switchig starts but Mike is right about adding a pre-charge resistor to get the chip to start up. Good luck.

0 Mike O' 26 days ago in reply to Peter Repka

TI__Guru 66135 points

Hello Peter,

I have seen that technique used and it works quite well.

Regards,

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UCC28056: supply voltage for PFC UCC28056