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LMG1210: How does bst diode capacitance affect loss/charging time etc in a bootstrap circuit?

Part Number: LMG1210

Thank you!

  • Hello Shengan,

    Less diode capacitance reduces the diode's reverse recovery charge. With less reverse recovery charge, the diode can change state faster and the diode can switch faster. I recommend using a Schottky diode for fast switching times.

    Best Regards,
    Ethan Galloway

  • Schottky for sure. But I am wondering which parameter is more important Trr or Cd, when switching at 25MHz, with very small GaN like EPC8010/EPC8009.

    for example, which one to choose between BAT46WJ,115 and PMEG10020ELRX

    Vdc

    Trr, ns

    Cd@1V

    Vf

    BAT46WJ,115

    100

    5.9

    21p@1V

    850 mV @ 250 mA

    PMEG10020ELRX

    100

    3.7

    70p@1V

    830mV@2A

  • Hi Shengan,

    That's a good question. I think the BAT46WJ,115 would be better. It has a lower capacitance and a similar reverse recovery time. Keep in mind the reverse recovery time for the PMEG10020ELRX​ is measured at 1 amp while the BAT46WJ,115​ reverse recovery time is measured at 10 mA.

    You should also consider switching losses vs conduction losses between the boot diodes as well.

    Best Regards,
    Ethan Galloway