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UCC28514: Generic questions

Mahesh KC03
Intellectual 1360 points
Other Parts Discussed in Thread: UCC28514

Hi team,

One of my customers is planning to use our UCC28514 PFC+DC/DC converter for a universal AC to DC output application. Below are a couple of queries. Can you please help me with the answers?

1. Can you confirm if we really need to use this high voltage transistor for start-up or only a bleeding resistor is sufficient?

2. Also QR mode Flyback control is preferred due to high efficiency requirement (>70% across all range). 

My comment is that the normal flyback using this device can achieve around 85% efficiency at 6A, 70W output. Do we really need a QR?

3. Can UCC2851x be used for CC/CV mode operation for battery charging?

  • 0
    TI__Expert 3200 points

    Hi Mahesh,

    You do not need the high voltage transistor for start-up but it helps improve the efficiency and even achieve consistent (or faster) start-up since the reference design had universal (85 - 265 VAC) input voltage.  The transistor makes the start-up circuit easier to design.

    The need for QR versus a conventional flyback is dependent on the customer efficiency requirements. A QR flyback yields better efficiency like you point out.

    You can design a CV/CC control but will require some knowledge on the battery characteristics needed and if too involved may be a challenge to design.