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UCC28951: Is a PSFB the best option for a Lithium battery charger?

HW_engineer_5678
Prodigy 75 points
Part Number: UCC28951

Tool/software:

Hello, I'm designing a battery charger and have selected a PSFB topology based on the IC UCC28951. However, during the design, I saw that LLC could have better efficiency. 
It seems that LLC has better efficiency, but it works better on a fixed output voltage. In my case the output voltage will have to change from 40V to 60V so I'm not sure if it will have a high impact on the efficiency. 
On the other hand, the PSFB has good efficiency but it's more expensive because it needs 4 HV fets and their drivers. 
Do you think that the LLC will have a big negative impact on the efficiency of this output voltage range?

  • 0
    TI__Guru 50090 points

    Hi Bangalii,

    What is the power level you are looking to support? In general you are correct in that the PSFB is traditionally better than an LLC for supporting a wider output voltage range. That being said, our new LLC the UCC25660 with IPPC (Input Power Proportional Control) makes it well suited to support a wider output voltage range while avoiding entering burst mode with low VBATT during the CC charging phase. 

    In the past when an LLC controller was used for a battery charging, to avoid entering burst mode with low VBATT, it would be used in an LCC configuration. While the LCC can support a wider output voltage range, it will have a lower efficiency compared to an equivalent power level LLC. The good news is that our new controller can support the wider output range as an LLC!

    We do have a reference design PMP23464 showing our new controllers capability. 

    I hope this answers your question.