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PMP11612: snubber temperature

Part Number: PMP11612


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

only difference is the fet:

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.

  • 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?
  • 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?
  • Hi,
    You can replace to S1J if you want. It should be a problem in thermal if the leakage inductance is higher.