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DRV3201-Q1 Internal pull-up of RSTN, DRVOFF, B_EN and NCS considering the Functional Fail-Safe (A-62)

Toshio Ushikubo
Mastermind 9620 points

Hello,

 

Following terminal have internal pull-up.

  1. RSTN

  2. DRVOFF

  3. B_EN

  4. NCS

Please advise why these terminals have pull-up, and is it all right under the condition of terminal’s open considering the Functional Fail-Safe.

(Please answer for each terminal.)

 

Best Regards.

  • 0
    TI__Guru** 114905 points
    Hi Ushikubo-san,

    Our experts have been notified and should reply soon.
  • 0
    TI__Expert 3555 points

    Hi Ushikubo-san,

    For each terminal, in case of a pin opened failure,

    1. RSTN : The device remains in active state because of the internal pull-up. This allows the gate driver to be controlled normally.

    2. DRVOFF: The gate driver is shutdown because of the internal pull-up. The gate driver goes to Fail-safe state (disabled) because the secondary shutdown path (DRVOFF) has a failure.

    3. B_EN: The device remains in active state because of the internal pull-up. This allows the gate driver to be controlled normally.

    4. NCS: SPI communication is disabled because of the internal pull-up. This is to prevent unexpected SPI communication due to the failure of the NCS pin.

    Regards,

    Will Toth

  • 0 in reply to William Toth
    Mastermind 9620 points

    Hello Will-san,

     

    Thank you for your answer.

     

    I can understand your answer for 2.DRVOFF and 4.NCS considering Fail-safe point of view.

    But I can’t understand answer for 1.RSTN and 3.B_EN.

    I think these should be pull-down and go to Reset and Boost disabled state because control signal is lost.

     

    Please explain the reason of pull-up for 1 and 3 again from the safety point of view.

     

    Best Regards.

  • 0 in reply to Toshio Ushikubo
    TI__Expert 3555 points
    Ushikubo-san,

    The DRVOFF pin (as well as the EN pin) is a primary shutdown path. Even without control of RSTN and B_EN you can shutdown the gate driver.

    NCS, RSTN, B_EN are not primary shutdown paths (you don't set B_EN=L for the purpose of shutting down the gate drivers). The result of a pin open for these is lost functionality, not loss of a critical shutdown path.

    Regards,

    Will Toth