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.

PMP21318: efficiency data

Part Number: PMP21318
Other Parts Discussed in Thread: UCC2897A, TPS2373

Dear team

I have refer the PMP21318.

https://www.ti.com/lit/ug/tidt301/tidt301.pdf?ts=1685622288968

The spec of customer  is Vin=54V,Vo=12V,Io=5A, They would like to know the efficiency of converter(UCC2897a).

Could I refer the yellow line value on test report(0A-5A)? 

And for this efficiency table. Did the J3 is efficiency include(TPS2373+ucc2897a)?

Did the J1 is efficiency include(full bridge+TPS2373+ucc2897a)?

https://www.ti.com/lit/ug/tidt301/tidt301.pdf?ts=1685622288968

Many thanks

Denny

  • Denny,

    Yes, the highlighted column is the efficiency of the UCC2897A active clamp forward converter with a fixed 48V input and load from 0 to 6A.

    The J3 efficiency is for the input at J3 (AUX).  it is the converter plus losses from the blocking diode D27.  It does not include the TPS2373.

    The J1 efficiency has the input at the RJ-45 connector.  It includes the PoE xfmr, bridge, hot swap FET in the TPS2373 and the UCC2897A.

    Thanks,

    David

  • Hi David

    Did you have the power loss under the main component(transformer、synchronous rectification、main mosfet)

    The spec is Vin=54V,Vo=12V,Io=5A

    Please refer the simulation result under webench. 

    https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=CDDDB615711EF81B

    The efficiency curver is about 89.5%. But the efficiency of PMP21318 is around 94%.

    I think use the synchronous rectification could improve the power loss. But around 5% efficiency difference will cause by which component?

     

    Many thanks

    Denny

  • Denny,

    At 94.4% efficiency and 6A load, the power loss in the converter is 3.56W.

    I estimated the power loss for the main power stage components for 48V input and 6A load.

    Primary FET...165mW

    Clamp FET...100mW

    Series Sync FET...330mW

    Parallel Sync FET...360mW

    Transformer...?

    Inductor...800mW (from Wurth web tool, mostly core loss)

    Rsense...250mW

    UCC2897A...150mW

    Secondary Snubber...180mW

    Secondary Clamp...160mW

    Without the transformer, the total converter loss is 2.495W.  This leaves 3.56-2.495 = 1.065W for loss in the transformer and other miscellaneous circuit losses.  1W of loss in the transformer seems reasonable.

    Thanks,

    David