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LM25119 - HS Gate Drive Bias Current

Brian Gosselin
Expert 4745 points

Hi Team,

The bias current on the high-side MOSFET gate drive is 100uA (max).  My customer's comment is that this is a little steep and ideally they would like to get 0A here.  They're using external VCC bias and would like to know if it is okay to remove the bias from one of the channels.  Is this okay or would it affect the other channel?

I did see the notes in the datasheet regarding "If VCC1 is in an under voltage condition, channel 2 is disabled."  Also, "if either VCC is in UV, both channels are disabled."  However, I'm not sure if this applies only when using the internal VCC bias or also when using an external VCC bias?

Also, can you please provide some information as to why the high-side MOSFET gate drive bias current is 100uA (max)?  What's driving this value in our controller?

Thanks in advance for your feedback.

Best Regards,
Brian Gosselin
AFA Boston, MA

  • 0
    TI__Mastermind 21720 points

    Hi Brian,

    The spec is meant to capture the bias current of the high-side gate drive and all the logic circuity around it. Think of it like the VIN operating current spec. So 0A is not really a reasonable spec. Lowering the VCC should decrease the bias current but the saving would be small. What is the reason that customer is worried about this spec?

    As for the question about the VCC UV, this would be for either external or internal VCC. The UV is looking at the actual VCC voltage.

    Let me know if you have any questions.

    Thanks,

    Garrett