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

Shengnan Li

Expert 1010 points

Part Number: LMG1210

Thank you!

over 1 year ago

0 Ethan Galloway over 1 year ago

TI__Genius 9570 points

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

0 Shengnan Li over 1 year ago in reply to Ethan Galloway

Expert 1010 points

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

0 Ethan Galloway over 1 year ago in reply to Shengnan Li

TI__Genius 9570 points

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

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