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DRV8873HEVM: Defective Unit

Daniel Palacio
Prodigy 20 points
Part Number: DRV8873HEVM
Other Parts Discussed in Thread: DRV8873

I'm currently trying to test out and evaluate this device. I've contacted support but apparently need to create a forum thread in order to verify if it's defective. Upon power up and verifying all the connections, the device appeared to work for a second and then stopped due to a fault condition. Since then however, I have been unable to get the device working as intended. I'm using the included software and USB cable to control the device. When taking the device out of sleep mode, a fault is immediately triggered. I remove open load detection and disable ITRIP, but still get a fault when taking it out of sleep. This happens in both PH/EN and Independent Half-bridge mode. In sleep mode, when changing over to PWM mode, a fault condition is immediately triggered and this is before I sleep mode is even disabled. The fault condition is noticed via the red LED on the board and through software. As I have the hardware version, I'm unable to determine what the actual fault is as it does not report specific fault data. Any help would be appreciated to verify defectiveness. My VM voltage is 18V and I confirmed that the motor is the correct type for this device and is fully functional. thank you in advance. 

  • 0
    TI__Mastermind 37683 points

    Hello Daniel,

    Thank you for posting to the forum.

    Let's try to first understand what type of fault is being triggered:

    • Are the outputs functional when the the fault is triggered? or does the motor stop spinning?
    • Can you check what the voltage of VCP is while the fault condition is triggered?
    • What is the VM voltage when fault is triggered?
    • Can you remove the motor load and try to drive the outputs? does the fault still get triggered?
    • Does cycling power OFF/ON remove the fault condition?
  • 0 in reply to Pablo Armet
    Prodigy 20 points

    Hi Pablo,

    I've tried this on two different power sources: a battery pack and a direct power supply. The VM voltage reads 18V so not noticing any voltage drop during a fault condition. Fault conditions happen on both power and battery sources. The outputs are not functional when a fault is triggered and I'm unable to get the motor spinning. Cycling on and off does not fix the fault condition. As for the VCP voltage and motor load I will check those out ASAP and reply back with that information. 

  • 0 in reply to Daniel Palacio
    TI__Mastermind 37683 points

    Hi Daniel,

    Thank you for the information. It looks like the fault is not UVLO. The other options are VCP undervoltage or OCP fault.

  • 0 in reply to Pablo Armet
    Prodigy 20 points

    Pablo,

    Here is the remainder information requested. With the motor not connected and disabling open load detection, I still get an fault condition. I measured the voltage at VCP and it was 17.2V. I was using a battery pack, and the voltage of the battery pack was 17.6V.I did this measurement during a fault condition. Hope this helps. 

  • 0 in reply to Daniel Palacio
    TI__Mastermind 37683 points

    Hi Daniel,

    Thank you for the information.

    Did you measure VCP with respect to board GND? If so, it looks like this is a charge pump undervoltage fault getting triggered. As you can see on the table below, a CPUV fault will be triggered if the VCP voltage is below VM+2.25V. In your case, the VCP and battery voltage are almost the same. This would explain why resetting the device is not clearing the fault since the VCP is always < VM+2.25V.

    The only way to know if the IC somehow got damaged would be to replace it with a new IC. But I don't think you have extra DRV8873 ICs. Am I correct?

    It's going to be difficult to determine if the device is damaged if you cannot replace it with a new one to test if the problem goes away. So I think you should contact customer support again and tell them to send you a new board.

    Once you receive the new board and the issue is still present, feel free to reply back to this post or create a new one and I'll be happy to help you figure out the root cause.

  • 0 in reply to Pablo Armet
    TI__Genius 16505 points

    Hi Pablo,

    This is a message from the customer support center.

    Does this mean the customer is now approved to proceed with the replacement process or we still need additional inputs from him?

    Thanks,

    Art

  • 0 in reply to Art Mecina
    TI__Mastermind 37683 points

    Hi Art,

    Yes the customer is approved, we can't do much debugging since the driver seems to be damaged.

  • 0 in reply to Pablo Armet
    TI__Mastermind 37683 points

    Hi Daniel,

    I will close this thread for now. Once you receive the new board can you please make sure to test it without any load at first. Once everything looks to be functioning, connect the load. If the failure is still present, then feel free to reply back to this thread or create an new one if this thread gets locked.

    Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    Prodigy 20 points

    Thank you Pablo. How do I track my replacement board? Is there a specific case number I can use when contacting customer support? I'd really like to get this is my hands ASAP to get back on track. Thank you in advance!

  • 0 in reply to Daniel Palacio
    TI__Mastermind 37683 points

    Daniel,

    I'm not sure how to track the board. You will have to contact customer support for that information.