LM5176: bootstrap junction cap

Fred Cheng

Part Number: LM5176

Hi team,

Is the average current and junction capacitance suitable for LM5176 bootstrap diode?

I heard that large junction cap may cause more reverse recovery loss.

Regards,

Fred

0 Stefan Schauer over 2 years ago

Hi Fred,

thank you for using the E2E forum.

Based on your question I am not sure if you mixing the bootstrap diode with the async. rectifier diode

The bootstrap diode in the LM5176 is this one (e.g. for Boot2)

Best regards,

Stefan

0 Fred Cheng over 2 years ago in reply to Stefan Schauer

Hi Stefan,

I am referring to bootstrap diode like I posted not async

would you help me check if the diode spec is suitable?

Regards,

Fred

0 Stefan Schauer over 2 years ago in reply to Fred Cheng

Hi Fred,

i think this quite over dimensioned then.

Please compare it with the diode used in the reference design: BAS316, BAS115.

Yes, the large junction cap will cause additional loss.

Best regards,

Stefan

0 Fred Cheng over 2 years ago in reply to Stefan Schauer

Hi Stefan,

our design Max Vin=36V, 36-7.35=28.65V >20V

does this violate the max reverse voltage of SK32AFL?

+1 Stefan Schauer over 2 years ago in reply to Fred Cheng

HI Fred,

yes, it will be violating this as the reverse voltage on this diode will be 28.65 V as you calculated.

Best regards,

Stefan

Power management forum