This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UCC28951: efficiency comparison between UCC3895 and UCC28950/1

Part Number: UCC28951
Other Parts Discussed in Thread: UCC3895, UCC28950, UCC2895

I am interested in using UCC28951 for an isolated AC/DC battery charging application (24V ~ 48V) supplying upto 1.3kW.

Please see screenshot of efficiency comparison between UCC3895 and UCC28951, which appears to have 94.3% efficiency at 40A current, which is done without a PFC circuit, I assume (with a constant DC input supply).

Was the efficiency curve on UCC28950 measured when using SR MOSFETs on the transformer secondary?

What is limiting the efficiency?  Is it possible to get higher efficiency when using this controller?

BTW, I couldn't post a related question to the efficiency curve, as I kept getting directed to post a new question.



  • Hello,

    The UCC2895 and the UCC28950 can both use SRs and can be designed for similar max load efficiencies.  I do not know who did the study of these two designs and what the requirements were.  However, the curve shows from 15 to 55 A the efficiencies of the two designs are almost identical.

    Below 15 A at light load the efficiency of the UCC28950 is higher.  This might be because the UCC28950 has a DCM function that will turn off the SRs under light loads when setup correctly.  So this will remove the switching losses of the SRs under lite loads and improve efficiency.  I think that is why you see the improvement at lite loads over the UCC2895 because the SRs are still on.

    Section 7.3.12 of the data sheet explains the DCM function and how to set it up.