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DRV8711: The selection requirements for MOSFET parameters (Vds, Rdson, Qg, etc.) for DRV8711 driver

Jon WANG
Intellectual 610 points
Part Number: DRV8711
Other Parts Discussed in Thread: CSD18531Q5A

Tool/software:

Dears,

    My customer wants to know what are the selection requirements for MOSFET parameters (Vds, Rdson, Qg, etc.) for DRV8711 driver? I couldn't find any relevant information on the datasheet, could you please help share it. thank you!

  • 0
    TI__Mastermind 44475 points

    Hi,

    Thank you for your questions. DRV can select driving current as follows.  Customer can choose the preferred setting from here and can check performance on the bench DRV + External FET.

    regards

    Shinya

  • 0 in reply to Shinya Morita
    Intellectual 610 points

    Shinya,

         Thanks.But what the customer wants to know is the parameters( Vds, Rdson, Qg, etc.) required by the external MOSFET to determine what MOSFET to choose.

  • 0 in reply to Jon WANG
    TI__Mastermind 44475 points

    Hi,

    CSD18531Q5A can be used as example. This FET is on DRFV8711 EVM

    www.ti.com/.../DRV8711EVM

    EVM schematic is here.

    CDS18512Q5B is another example.

    regards

    Shinya

  • 0 in reply to Shinya Morita
    Intellectual 610 points

    Shinya,

        I know these EVM board and know use CSD18531Q5A and CDS18512Q5B.But my customer want to know how to choose the external Mosfet? For example,if the voltage of motor is 48V,current is 1A, What parameters of MOSFET should be selected? Does Vds require 60V or 80V? Or higher? How much does Rdson/Id require? Are there any requirements for parameters such as Qg and Ciss,Coss,Crss?

  • 0 in reply to Jon WANG
    TI__Mastermind 44445 points

    Hi Jon,

    Have you reviewed the datasheet section 8 Application and Implementation which provides application design details and specifically section 8.2.2.3 Support External FETs?  

    Jon WANG said:
    For example,if the voltage of motor is 48V,current is 1A, What parameters of MOSFET should be selected? Does Vds require 60V or 80V? Or higher?

    The absolute maximum ratings for Power supply voltage VM for the DRV8711 is 60 V MAX. So MOSFET ≥ 60 V should be fine. 

    Jon WANG said:
    How much does Rdson/Id require?

    This would depend on the power dissipation due to I2Rdson and switching losses, TA ambient operating temperature requirements of the application design. Usually power MOSFETs are very low Rdson sub 10 mΩ may be even sub 5 mΩ and can support several amps of motor current.   

    Jon WANG said:
    Are there any requirements for parameters such as Qg and Ciss,Coss,Crss?

    Like mentioned previously, the DRV8711 can accommodate a wide range of these parameters because of programmable nature of IDRIVEP, N and TDRIVEP, N. Calculations are provided in the application section of the datasheet. Thank you.

    Regards, Murugavel