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DRV8461: Overcurrent protection

Hiroaki Yuyama TED
Expert 1560 points
Part Number: DRV8461
Other Parts Discussed in Thread: DRV8711

Tool/software:

Dear Support Team.

We are investigating whether our customer can set the current limit value of the DRV8461 arbitrarily.
As far as I read in the data sheet, there is no resistor or external resistor that allows the current limit value to be arbitrarily set.
Can the current limit value of the DRV8461 be changed?
Also, are there any stepper motor drivers that can change the current limit value?
Thanks & Best regards,
Hiroaki Yuyama
  • 0
    TI__Mastermind 32685 points

    Hi Yuyama-san,

    Hiroaki Yuyama TED said:
    Can the current limit value of the DRV8461 be changed?

    This parameter is hard coded in the device and cannot be modified by the user.

    Hiroaki Yuyama TED said:
    Also, are there any stepper motor drivers that can change the current limit value?

    The stepper motor gate driver device DRV8711 has programmable option for OCP detection which is done by VDS voltage threshold based OCP monitoring. The values are programmable to one out of four options that are hard coded in the device. I'd recommend customer to review this and see if this would intersect with their requirements.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Expert 1560 points

    Hello Murugavel-san,

    Thank you for your reply.
    I understand that the overcurrent protection current value of the DRV8461 cannot be changed.

    And I understood that the DRV8711 can limit the current by the voltage drop of the VDS of the FET.
     When I read the datasheet, I found that the OCP can be set by the voltage drop of VDS, but there are four different register settings.

    The customer requires open-load detection as a device specification.
    Does the DRV8711 have the function of open-load detection?

    If there is a stepping motor driver that has an open-load detection function and can set the current limit, please let me know.

    Best regards,
    Hiroaki Yuyama

  • 0 in reply to Hiroaki Yuyama TED
    TI__Mastermind 32685 points

    Hi Yuyama-san,

    Hiroaki Yuyama TED said:
    Does the DRV8711 have the function of open-load detection?

    The DRV8711 uses external power MOSFETs. It does not support open load detection.

    Hiroaki Yuyama TED said:
    If there is a stepping motor driver that has an open-load detection function and can set the current limit, please let me know.

    This combination does not exist with our current portfolio of stepper drivers. What is the range of current limit that customer would like to set? What is the purpose? I can explore other dual H-Bridge options should there be a fit. However in this case the customer may have to develop there own stepper control logic to drive the H-Bridges from their MCU. Let us know. Thank you.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Expert 1560 points

    Hello Murugavel-san,

    Thank you for your suggestion.

    The purpose is the working part of the stage of medical products.

    Here's why I need current limiting.
    I want to make sure the stepper motor doesn't pass more current than its rated current.
    The rated current of a stepper motor is 250mA.
    So I'm looking for a stepper motor driver that can limit the current to 250mA, not make it variable.

    We are looking for a 250mA current limit in a stepper motor driver.
    The open load detection feature has secondary priority.

    Best regards,

    Hiroaki Yuyama
  • 0 in reply to Hiroaki Yuyama TED
    TI__Mastermind 32685 points

    Hi Yuyama-san,

    A current limit requirement of 250 mA is not possible to be programmed in integrated stepper drivers. Customer must design external circuits to do this. Thanks for the clarification. BTW, when the IFS is set to 250 mA with VREF there is no way current will exceed 250 mA unless the device is damaged or shorted. 

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Expert 1560 points

    Hello Murugavel-san,

    Thank you for your advice.

    We will set the current limit value in IFS in the TRQ_DAC settings in the Current Regulation function of the DRV8461.
    We continue the design with the DRV8461 with open load detection.

    The stepper motor used by our users is the link below.
    https://docs.rs-online.com/3c22/0900766b8148c93a.pdf

    Best regards,
    Hiroaki Yuyama