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.

DRV11873: If the motor has a low-speed reversal, the current will generally be larger (basically around 700ma), the chip is a little hot

Part Number: DRV11873

Hi Engineer,

When we use the DRV11873, there are about 5 or so, and the chip is damaged. The specific situation is:

DRV11873-E2E-en.docx

  • Hey Elsa,

    Can you say in greater detail what you mean by low-speed reversal? Does that mean that while the motor is spinning, some external torque spins it reverse? Or is the motor driver driving the motor backwards initially? Or is the motor spinning backwards before the motor driver starts trying to spin it?

    Sincerely,
    Sanmesh U.
  • Hi Sanmesh,

    Thanks for your attention.

    The whole process only controls pwm, and the direction is fixed by hardware;


    Not because of improper use of welding and production staff;


    The low speed reversal is not caused by external torque, and the motor load will not change during the whole process!
    In the original design, the current limiting resistor was 3.3k, but at the time there was a chip damage, thinking that the current was too large, so the current limiting resistor was replaced by 3.9k. After replacing the resistor, it is easier to reverse. However, it is not the external force or the control reversal, but the motor automatically rotates in the opposite direction, and at this time, the maximum motor speed can only reach 200 rpm!
    At present, I think it should be some kind of error when starting up, such as starting current is too large, but not sure, now it will reverse for up to 10 seconds in normal use, the program will shut down the motor;
    When the reversal occurs, the chip is a little hot, but it runs for several hours at 80 high temperatures, and it is not damaged (not to rule out individual differences, after all, I only tested a few, and the site only damaged a few)!


    A total of one or two hundred units, two damages occurred, and the inside of the sealed case is the case that the pad is burnt out.


    U2 is 11873, the heat sink pads on the pcb are burned out, and the above several vias are broken.

  • Hey Elsa,

    Let me talk to my teammates about this and get back to you tomorrow. I apologize for the delay.

    Sincerely,
    sanmesh U.
  • Questions:

    1)  What is the particular case that this problem happened? Is it when the motor was spinning in the correct (not reverse) direction and at 80 degrees? Is the 80 degrees celsius or fahrenheit?

    Things to check:

    1)Make sure V5 isnt being loaded more than 20mA. If it is loaded more than that, than maybe the FR pin is not high and is telling the device to go the wrong direction sometime. Also check the voltage of V5

    2) I think getting a scope capture of one of the motor phase currents would help to see if it is abnormal and causing the device to heat up

    Notes on what you have told so far are attached. Feel free to correct them if I'm wrong.

    DRV11873-E2E-enV2.docx

  • I will close this for now since I havent heard back, but if you have any questions, respond to this thread or create a new one.
  • Sorry to reply late.
    5V does not exceed 20ma, it is only used in several pull-up resistors of DRV11873.
    I've been constantly powering up the device, and then power off (once a minute, once in about four hours), and then I found that the electrorheological changes, chip heating, DRV11873's 5V output slowly increased (5.3V, 5.6V, 6.1V...), and then the chip completely burned!
    Please help me to analyze the possible reasons for this situation.
  • One of the reasons I think the device is getting hot and damaged is that it is a result of the V5 pin increasing and being above the 6V absolute max.
    As per what is causing the V5 pin to output a higher voltage, this needs to be explored further.
    1) When you did your on/off test, was a motor connected or disconnected? If it was disconnected, then that means that the problem is independent of the algorithm spinning the motor. So it is probably a board problem then. Make sure to o
    2) Make sure the V5 isnt being damaged by applying a Vcc above 20V absolute max. Sometimes, a voltage spikes happens when powering up a power supply, so if you find in question 1 above that the problem is happening with the motor disconnected, then maybe monitor the Vcc pin with the oscilloscope and see if there is a voltage spike happening, especially when powering up the power supply
  • I measured the power supply, we are 12V power supply, is surge and burr, etc., not more than 14v.

    In addition, last Friday, I paralleled the Schottky tubes on the UVW and tested them for about 10 hours. So far, they have not been damaged.

  • Hey elsa,

    1) shottkey diodes on the motor phases fixing the issue might indicate the damage is coming from voltage surge from the motor through the motor phase pins. You can learn more about this from this datasheet ( www.ti.com/.../drv10987.pdf ) 8.4.9 Anti-Voltage Surge Function
    2) When you did your on/off test, was a motor connected or disconnected? If it was disconnected, then that means that the problem is independent of the algorithm spinning the motor as well as independent of the motor.

    Hopefully the schottkey diodes fix your issue.

    Sincerely,
    Sanmesh U.
  • Hey elsa,

    Were you able to figure out the solution, or any further help needed?

    Sincerely,
    Sanmesh U.
  • I will close this thread since I havent recieved a response. If you need further followup, please either reply to this thread or create a new thread.