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PMP11612: snubber temperature

Lu Ha
Prodigy 150 points
Part Number: PMP11612

hello,

we use an almost identical circuit like pmp11612 and our snubber temperature reach 95° C under full load.

only difference is the fet: datasheet.lcsc.com/.../Wuxi-NCE-Power-Semiconductor-NCE65T1K2I_C181922.pdf

and regarding to the design files, the snubber only reached 75° C while testing from TI.

is our transformer leakage too big? we made custom transformers based on the sumida 10339 - t048 sheet.

  • 0
    TI__Prodigy 470 points
    Hi,
    Which part in snubber going high temperature?
    Yes, the "leakage inductance" of the transformer will cause the voltage spike on the MOSFET. If bigger leakage inductance, should be higher voltage on that. But the voltage spike not only from leakage inductance, also comes from some parasitic parameter. The ESL of layout trace, Coss of MOSFET... etc. Base on your datasheet of MOSFET, I see the parameter of Coss is different from original one. Do you have the waveform on the Vds of MOSFET?
    Regards,
    LC-YIN
  • 0 in reply to Richard Yin
    Prodigy 150 points
    i will check it. but the leakage of our custom transformers seems to be too high. is there a problem in replacing DFL1600-7 with Diodes S1J?
  • 0 in reply to Lu Ha
    TI__Prodigy 470 points
    Hi,
    You can replace to S1J if you want. It should be a problem in thermal if the leakage inductance is higher.