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DRV3256-Q1: IDrive Reduce min drive current

Michael Reilly
Prodigy 196 points
Part Number: DRV3256-Q1
Other Parts Discussed in Thread: CSD19536KTT,

Hello, 

Trying to understand IDRIVE and how to reduce the rise time. The min setting of the pullup current is 1.5A and I am using the CSD19536KTT with a 17nC Qgd charge, so the min rise time would be 11nS which is causing ringing. Is the Idirve sourced from a resistor or how can the current be reduced below the min? I am hoping the addition of an external gate resistor can accomplish this but if it is a constant current source I don't think that would reduce the rise time. Please advice. 

Thanks

  • +1
    TI__Mastermind 19875 points

    Hi Michael,

    Thank you for your question! Since the DRV3256-Q1 is a device covered under NDA, I am unable to go into too many specifics on the public E2E form. However, the attached app note below gives an overview of how IDRIVE works which may give you the information you are looking for. Adding a gate resistor can slow down the current (and therefore reduce your switching speed) as long as the gate resistance is high enough.

    https://www.ti.com/lit/an/slva714d/slva714d.pdf?ts=1708024954468&ref_url=https%253A%252F%252Fwww.google.com%252F

    Another option is to add some additional Cgd capacitance to increase the effective Qgd and slow down the FET switching time. Keep in mind that this will change the Qgd/Qgs ratio which could increase charge coupling into the FET that is off.

    Given that this device is covered under NDA, if you need more specific details you can reach out to your TI FAE (if you are not sure who he is then let me know) and the FAE can work with us to get your questions answered.

    Regards,

    Anthony Lodi