• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Subscribers 29 subscribers
  • Views 967 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8818 Issue at Mixed decay operation

masahiko shimizu
Guru 11235 points
Other Parts Discussed in Thread: DRV8818EVM, DRV8818

Hi

I operate motor by DRV8818EVM in the following condition.
- 3000pps
- 24V
- 1.5A
- 1/2 step

In this condition, in only Mixed decay case, motor can not be operated.
I would like to get advice about cause of this issue.

Please see the following waveform.
Figure 1 is Slow decay.
Figure 2 is Fast decay.
Figure 3 is Mixed decay.

DRV8818.pptx

Best regards,
Shimizu

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

    Can you provide some additional information?

    1) A schematic of the DRV8818 and surrounding components.
    2) A scope capture of the current, the output voltages, and the HOMEn pin
    3) A scope capture of the current in both windings
  • 0 in reply to Rick Duncan
    Guru 11235 points

    Hi Rick-san,

    Thank you for your support.
    I answer as the following for your question.


    >1) A schematic of the DRV8818 and surrounding components.
    Ans) Schematic is EVM. But I changed R value for Toff.
    R5 and R7 is 37.5k-ohm.
    Other parts is same default EVM.

    >2) A scope capture of the current, the output voltages, and the HOMEn pin
    Ans) I took the this picture as attached file(Figure 1 - 4)

    DRV8818_Answer_of_Q2.pptx

    >3) A scope capture of the current in both windings
    Ans) I'm sorry. I don't have two current probe.
    I took picture each windings as attached file(Figure 5 - 8) only mixed decay.

    DRV8818_Answer_of_Q3.pptx

    Thanks
    Shimizu

  • 0 in reply to masahiko shimizu
    TI__Guru** 114905 points
    Hi Shimizu-san,

    Thank you for the information. The HOMEn pin is asserting at incorrect times. This indicates a fault is being detected (overcurrent, thermal shutdown, undervoltage).

    Can you add the AOUT2 voltage in slides 1 and 2 of Q3 and zoom in further?
    Can you add the BOUT2 voltage in slides 3 and 4 of Q3 and zoom in further?
    Also, what is the VREF voltage?

    Is this behavior seen on multiple boards? If not, is it possible the device has been damaged?
  • 0 in reply to Rick Duncan
    Guru 11235 points

    Hi Rick-san,

    Thank you for your support.
    I answer as below.

    >Can you add the AOUT2 voltage in slides 1 and 2 of Q3 and zoom in further?
    Ans) Please see the attached file(Fugire 1 - 4)

    DRV8818_Answer_of_Q3-2.pptx

    >Can you add the BOUT2 voltage in slides 3 and 4 of Q3 and zoom in further?
    Ans) Please see the attached file(Fugire 5 - 6)

    >Also, what is the VREF voltage?
    Ans) 1.2V

    >Is this behavior seen on multiple boards? If not, is it possible the device has been damaged?
    Ans)It is minority. it is possible the device has been damaged.
    I changed IC from EVM's default IC to customer IC.
    Now I analysis.

    I think fast decay's waveform is incorrect, too.
    Please see the first post attached file.
    and the following picture is fast decay.
    Is red circle operation correct?

    Best regards,
    Shimizu

  • 0 in reply to masahiko shimizu
    TI__Guru** 114905 points
    Hi Shimizu-san,

    The operation in the circle does not appear to be correct.

    Please provide the lot trace code for the customer device.

    Thank you.
  • 0 in reply to Rick Duncan
    Guru 11235 points
    Hi Rick-san,

    Thank you for your support.
    I understand this IC is incorrect operation.

    Lot trace code is "4ATC" "CH57".

    Just for information.
    We have promoted the procedure of TI analysis.

    Thanks,
    Shimizu
  • 0 in reply to masahiko shimizu
    TI__Guru** 114905 points

    Hi Shimizu-san,

    Do you have an update on the device status?

    Thank you.

  • 0 in reply to Rick Duncan
    Guru 11235 points

    Hi Rick-san,

     Thank you for care.

     We have proceeded with the procedure for analysis through TI Japan sales.

    Thanks,

    Shimizu