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DRV8462VEVM: DRV8462_Manufal VREF

Darshan TH
Prodigy 10 points
Part Number: DRV8462VEVM
Other Parts Discussed in Thread: DRV8462

Tool/software:

Hi,

We are designing custom motor driver board using DRV8462DDWR IC, 

Regarding VREF connection, Used Voltage divider circuit using Two 10K Resistor.(as per Development board and Typical application circuit) 

1. Is that okay for driving the stepper motor?

2. Based on the Motor Capacity is it required to change the divider voltage? 

3. How to check the functionality of the  MANUAL_VREF in the DRV8462VEVM development board. and what jumper modifications required? (J6 to be removed and Put it to the J7) 

Kindly suggest if any other modifications required in the Hardware or GUI setting.

Regards

  • 0
    TI__Mastermind 44595 points

    Hi Darshan,

    Thank you for contacting us via this forum.

    Darshan TH said:

    Regarding VREF connection, Used Voltage divider circuit using Two 10K Resistor.(as per Development board and Typical application circuit) 

    1. Is that okay for driving the stepper motor

    The DRV8462 supports an internal VREF = 3.3 V for 5A full-scale current IFS in DDW package or 10A IFS in DDV package with TRQ_DAC setting at 100%. It also supports an external VREF input via the VREF pin. The voltage on the VREF pin determines the IFS current with TRQ_DAC setting at 100%. With two 10kΩ resistors based voltage divider at VREF, the VREF voltage would be VCC/2. If VCC is 3.3 V this would mean 1.65 V or an IFS current setting of 2.5 A. This should be okay for stepper motors requiring a 2.5 A current drive for the desired torque output.

    Darshan TH said:
    2. Based on the Motor Capacity is it required to change the divider voltage? 

    Matching the IFS to the stepper motor rated current will be needed to realize the rated torque output of the motor. 

    Darshan TH said:
    3. How to check the functionality of the  MANUAL_VREF in the DRV8462VEVM development board. and what jumper modifications required? (J6 to be removed and Put it to the J7) 

    Correct J6 jumper short must be removed and J7 jumper short must be populated. See below. This will set the VREF to 1.65 V or IFS = 2.5 A with TRQ_DAC = 100% (default). The GUI current setting does not affect the VREF voltage after this jumper short modification.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Prodigy 10 points

    Hi Murugavel,

    Condition 1:

    I removed the J6 Jumper and Placed in to the J7, After that open the DRV84XX -EVM GUI and selected the SPI interface,

    In GUI enabled the Motor Driver ,Step Edge, Auto micro stepping, RES_Auto settings.

     When enabled the Driver Outputs , DRV8462VEVM Draws more current from the Power supply. (2.7A) current.

    Condition 2:

    Removed the J6 and J7 Jumper in the GUI In CTRL_13 Register 1st bit  made it 1.  (VREF_INT_EN =1)

     When enabled the Driver Outputs , DRV8462VEVM Draws more current from the Power supply. (2.7A) current.

    Condition 3:

    Removed J6 and J7 jumper, and  VREF_INT_EN = 0 and this condition we can able to RUN the motor.

    Please help us to solve this issue, In custom board we have not used any DAC to set the REF voltage.

    Please share you mail ID will schedule a call to discuss the above issue.

    Thanks and Regards

  • 0 in reply to Darshan TH
    TI__Mastermind 44595 points

    Hi Darshan,

    Darshan TH said:

    Condition 1:

    I removed the J6 Jumper and Placed in to the J7, After that open the DRV84XX -EVM GUI and selected the SPI interface,

    In GUI enabled the Motor Driver ,Step Edge, Auto micro stepping, RES_Auto settings.

     When enabled the Driver Outputs , DRV8462VEVM Draws more current from the Power supply. (2.7A) current.

    This is expected behavior. When you removed J6 and populated with J7, VREF will be voltage divided from 3.3V using two 10kΩ resistors which would be 3.3/2 = 1.65 V. For the DRV8462 DDV package device this would mean a current setting of 5 A full-scale current IFS. If you need lower current you can reduce the % in the Torque DAC setting or you can reduce the value of R49 to a desired value. I tried the same with the EVM and it works as described which is expected behavior.

    Darshan TH said:

    Condition 2:

    Removed the J6 and J7 Jumper in the GUI In CTRL_13 Register 1st bit  made it 1.  (VREF_INT_EN =1)

     When enabled the Driver Outputs , DRV8462VEVM Draws more current from the Power supply. (2.7A) current.

    When internal voltage reference is enabled VREF will be 3.3 V. This would set the IFS current to 10 A. If you'd want lower IFS with internal reference you should change the Torque DAC setting. 

    Darshan TH said:

    Condition 3:

    Removed J6 and J7 jumper, and  VREF_INT_EN = 0 and this condition we can able to RUN the motor.

    Please help us to solve this issue, In custom board we have not used any DAC to set the REF voltage.

    Please share you mail ID will schedule a call to discuss the above issue.

    This is not an issue. the VREF pin has residual charge hence it has the last set value. It is a high impedance input pin. For a true zero you must GND the VREF, pin-1 of J6. Then the motor will not run. A DAC is not needed to set the VREF. It can set by two resistors similar to the J7 setting. Most designers provide VREF using this approach.

    We provide priority support over this forum. Please let's continue our discussion in this forum. Thank you.

    Regards, Murugavel