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LM5176: how to choose bootstrap diode

Ann_Lien
Genius 14340 points
Part Number: LM5176
Other Parts Discussed in Thread: PMP30549

Hello expert,

My customer need to know how to choose bootstrap diode on LM5176. I searched from ti.com and found out one application note which describes I_peak on diode = Cboot*dv/dt. http://www.ti.com/lit/an/slua887/slua887.pdf

But I didn't know how to choose average current level for bootstrap diode. Could you kindly help to let us know what is the criteria on I_peak and I_average for bootstrap diode? Thanks a lot!!

Best regards,

Ann Lien

  • 0
    TI__Mastermind 30955 points

    Hi Ann Lien,

    A general rule of thumb is to use a diode with an average rating higher than 250mA. The reason for this is that while the peak driver strength is high (2.2A), it is on for a very short time, so the average current being drawn is very little. In that case, the average current level for the bootstrap diode is also very small.

    If you look at PMP30549, you will see that the bootstrap diode has an average current rating of 0.25A. 

    Please let me know if you have any other questions.

    Thanks,

    Richard