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Original question:

DRV8711: Assistance with DRV8711 DC Motor Driver Issues

DRV8711: DRV8711: DC Motor Not Running After Switching to IRLS4030TRLPBF MOSFETs

Dhivya S
Prodigy 40 points
Part Number: DRV8711

Tool/software:

For the continuation of the thread "DRV8711: Assistance with DRV8711 DC Motor Driver Issues":

The DRV8711 was previously connected to AUIRF540ZSTRL MOSFETs, and the motor was functioning correctly. However, after replacing the MOSFETs with IRLS4030TRLPBF mosfet to meet the current requirements with load , the motor is not running, despite using the same configuration that worked with the AUIRF540Z MOSFETs.

Could you kindly provide suggestions or modifications needed to make the motor work with the IRLS4030TRLPBF MOSFETs.

  • 0
    TI__Mastermind 18820 points

    Hello,

    Although the current ratings are suitable for the load, it looks like the gate to source voltage, VGS, is larger for IRLS4030TRLPBF and will require a higher gate voltage to turn on. I suggest measuring the gate to source voltage and make sure it's large enough to bias both FETs. 

    Best,

    David

  • 0 in reply to David Medis
    Prodigy 40 points

    Hi sir,

    The gate-to-source voltage of the AUIRF540ZSTRL is ±20V, while the gate-to-source voltage of the IRLS4030TRLPBF is ±16V.

    When we attempt to operate the system through the DRV8711 in PWM mode, it does not work. However, it runs successfully in open-loop with a direct power supply. Kindly provide suggestions or guidance on the necessary implementation to make the IRLS4030TRLPBF MOSFET work in PWM mode.

  • 0 in reply to Dhivya S
    TI__Mastermind 43985 points

    Hi Dhivya,

    Dhivya S said:
    The gate-to-source voltage of the AUIRF540ZSTRL is ±20V, while the gate-to-source voltage of the IRLS4030TRLPBF is ±16V.

    These are the absolute maximum specifications for these FETs, not the operating voltage. These don't matter. What matters are the VGS threshold and the Qg specifications. The VGS threshold of the 4030 is 2.5 V max vs. 4 V for the 540. Both are lower than what the DRV8711 can provide. This would be a non-issue.

    The Qg of the IRLS4030TRLPBF is higher than the AUIRF540ZSTRL. This means it requires higher current drive setting. Please refer to section 8.2.2.3 Support External FETs in the datasheet, page-35.

    A potential solution could be to increase IDRIVEP and IDRIVEN settings and if needed also TDRIVEP and TDRIVEN settings. Thanks.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Prodigy 40 points

    Hi sir,

    Thanks for  your reply!

    DRIVE Register: 0x650F 

    Please verify the above value of the register.

  • 0 in reply to Dhivya S
    TI__Mastermind 43985 points

    Hi Dhivya,

    Dhivya S said:
    DRIVE Register: 0x650F 

    This translates to lowest TDRIVEP and N as following values for IDRIVEx settings.

    Like I mentioned previously "Please refer to section 8.2.2.3 Support External FETs in the datasheet, page-35." use the formulae in this section to calculate the required settings for your MOSFETs.

    I think you can try setting TDRIVEP and N to 1 μs and increase IDRIVEP and N. For example, try setting 0x6AAF and if that does not resolve try 0x6FAF and if not 0x6FFF. 

    While the motor is not running with the 0x650F setting can you read the STATUS register and see if APDF or BPDF bits were set? Please share the STATUS register value read for each setting 0x650F, 0x6AAF, 0x6FAF and 0x6FFF. Thanks.

      

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Prodigy 40 points

    Dear Sir,

    I tried different configurations based on your suggestions, but the value of the status register bits value (0) didn't change.

  • 0 in reply to Dhivya S
    TI__Mastermind 43985 points

    Hi Dhivya,

    If APDF or BPDF bits were not set in the STATUS register means the gate drive was normal. Did increasing IDRIVEP and IDRIVEN solved the output issue? Can you please provide oscilloscope captures for the following nodes while the device is actively driving - see below. Thank you.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Prodigy 40 points

    AOUT1A1HSA1LSAISENPA1SENNA2LSA2HSA2OUT

    these are images for your reference

  • 0 in reply to Dhivya S
    Prodigy 40 points

    hello sir,

    we are in need of your support for BDC motor, after setting the full torque register value as 0XFF still the full scale current is not driven by driver to motor 

    and our rsense register value is also 0.01ohm.

  • 0 in reply to Dhivya S
    TI__Mastermind 18820 points

    Hi Dhivya,

    It's difficult to tell from the scope captures provide which signal is which. Can you please add labels to these images? If following in order from Murugavels suggested nodes of capture, it looks like x2HS is the only gate that is seeing any voltage. Also please include input control sequence. Is the motor trying to be driven in forward or reverse (with or without PWM)?

    Best,

    David