Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

  • State TI Thinks Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 2 answers
  • Subscribers 48 subscribers
  • Views 802 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.

INA180: Schematic review

Deepak NS NS
Prodigy 140 points
Part Number: INA180
Other Parts Discussed in Thread: DRV8837

Hello team,

Here i am attaching the schematics of our new design. anyone please review it and let me know your comments.

Thank you..SMART ROD_SLOT_SCH_Review.pdf

  • 0
    Guru 140200 points
    Hi Deepak,

    why do you have the INA180 shunt twice in your schematic (R10 and R22)?

    Kai
  • 0 in reply to kai klaas69
    Prodigy 140 points
    Hi Kai,

    R22 is the actual shunt resister, at a time we mount only R22 or R10, R10 is used to measure the current directly
  • 0 in reply to Deepak NS NS
    TI__Mastermind 24005 points
    Hello Deepak,

    Thanks for considering to use Texas Instruments. So I interpret your above statement as R10 is for debug and R22 is for final system operation and only R22 will be installed. If R22 is the intended shunt with R10 depopulated, then I presume your current measurement range must be between 1.8mA and 293mA. One particular item I am concerned with is the output of the INA180 as it appears to be shorted directly to VM of your DRV8837. I presume this is a typo. However, if this actually was intended, I would like to better understand why you are doing this. Also can you elaborate on the net naming convention P-x, for instance P-4,5.
  • 0 in reply to Patrick Simmons
    TI__Mastermind 24005 points
    Hello Deepak,

    I have not heard from you in a while. Therefore I presume, you are satisfied with our review and have no further questions. As such, I am closing this thread. However, if you do need further assistance, please provide us with feedback below to reopen the thread.
  • 0 in reply to Patrick Simmons
    TI__Mastermind 24005 points

    Hello Deepak,

    I see that you still need assistance.  I presume you meant to upload a new schematic to your original post.  From what I can tell it is the same schematic.  As such I suspect the new schematic you tried to upload had the exact same name.  I have noticed that when I upload an image in a thread with the same name of an image uploaded previously in the thread, the old image is retained.  Therefore, I suspect a similar behavior for pdfs.  Therefore, can you re-upload your new schematic with a slightly different name?  However, if the schematic displayed now is different.  Please indicate how so.  From what I see you still have your INA180 output shorted to the INA180 input.

  • 0 in reply to Patrick Simmons
    Prodigy 140 points

    Dear Patrick,

    Here I am attached the renamed schematics. please find the schematics.

    Thank you..

    SMART ROD_SLOT_SCH_Review06may2019.pdf

  • 0 in reply to Deepak NS NS
    TI__Mastermind 24005 points

    Hello Deepak,

    There are actually multiple problems I see.  One issue will be you likely will not see the potential you expect at Rsense in- if you keep R24 populated.  Below, I illustrate the voltage discrepancies that will likely lead to a larger current draw from the 3.3V supply than anticipated. Below I assumed IVM of the drv8837 is 40uA.  

    Assuming you remove R24, you still may have problems as the Vsense voltage may not be sufficient without some sort of calibration.  The input voltage offset of the INA180 could be anywhere from 100uV to 500uV.  Consequently if the Ivm of the drv8837 is 40uA your % measurement error would range from 446 to 2232%.  However if Ivm of the drv8837 is closer to 1.5mA, then your % measurment error might only range from 12 to 60%.