• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 29 subscribers
  • Views 416 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

DRV8231A: Why the motor current of DRV8231A is different from DRV8870

Fengyu Leng
Intellectual 1875 points
Part Number: DRV8231A
Other Parts Discussed in Thread: DRV8870

Hi team,

We want to replace DRV8870 with DRV8231A. We were testing DRV8231A and found that motor current controlled by DRV8231A was smaller than that controlled by DRV8870 when the motor speed is relatively low.

Not much difference at high speed. Test result as attached picture.

Could you please tell me why motor current is different? And if there are some differences between DRV8231A and DRV8870 which we need to pay attention to.

Best regards,

Fengyu

  • 0
    TI__Mastermind 37683 points

    Hi Fengyu,

    What is the current regulation limit for both of the drivers? Are you using an evaluation board for both drivers?

    Fengyu Leng said:
    We were testing DRV8231A and found that motor current controlled by DRV8231A was smaller than that controlled by DRV8870 when the motor speed is relatively low

    Based on the images, it looks like the DRV8231A current is higher. Did I misinterpret the waveforms?

    The DRV8870 and DRV8231A have different current sensing architectures. The DRV8231A comes with integrated current sensing which eliminates the need of the sense resistor. 

    Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    TI__Intellectual 1875 points

    Hi Pablo,

    Thanks for your reply. As you mentioned, the current regulation limit of both DRV8231A and DRV8807 are 1A. But I didn't test them on EVM.

    After i read datasheet, I found some possible reason which I want to confirm with you.

    As datasheet of DRV8231A mentioned in 8.4.2.1, current sensing result is the current flows from drain to source in the low side mosfets. When work conditions are 1Forward drive and 2Brake, if the current sensing result is the current flows through Mosfet 4 as the following picture?

    But when we use DRV8870, external sample resistance can only sense the current of work condion1-Forward drive. When it converts to 2Brake, sample resistance can't sense current, so the result is 0A during 2Brake stage.

    Is my understanding correct? Thanks!

    Best regards,

    Fengyu

  • 0 in reply to Fengyu Leng
    TI__Mastermind 37683 points

    Hi Fengyu,

    Your understanding is correct about the current sensing between the two devices. During breaking, current sensing is not possible for the DRV8870 but possible for the DRV8231A. 

    It looks like the reason for overall lower current, measured from current sense output for each device, with the DRV8870 is due to the SENSE voltage dropping to 0-V during BREAK. However, if the motor current for each driver is measured with a current probe, the current will be similar in both case.

    Regards,

    Pablo Armet