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DRV8711: How to calculate IDRIVE

HM
Intellectual 460 points
Part Number: DRV8711
Other Parts Discussed in Thread: CSD18531Q5A

Hi,


I have a question about how to calculate IDRIVE on the EVM.

In the data sheet of FET(CSD18531Q5A) which is installed, the gate charge is specified as 18 nC, and the rise time is specified as 7.8 ns.

Calculating with the calculation formula(IDRIVE > Q / RT) described in the data sheet will result in IDRIVE > 2.3A.

Perhaps I believe that the rise time is not appropriate and I think we should set a longer time. 

Although "desired rise time" is described in the data sheet, how should we set the rise time?

Best Regards,
HM

  • 0
    TI__Guru 56650 points
    HM,

    The CSD18531Q5A rise time is specified as 7.8 ns means the rise time could be 7.8ns if you provide infinity drive capability, for example: the driver can give >2.3A capability. It doesn't mean you give less current to get that 7.8ns rising time. Actually, you may not want to turn on the FET too quick.

    Yes. The FET's 7.8ns rise time is not appropriate to use here and it should be set a longer time.

    If you know the desired rise time, you can calculate out the IDRIVE. If you don't have the EMI noise concern, you can pick a higher IDRIVE setting.