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DRV8412: Over-current limit cut in half at cold (-30C or below)

SheldonTT
Prodigy 225 points
Part Number: DRV8412

Hello,

I am using the DRV8412 on multiple designs. I have run into an issue while testing at cold with some of the DRV8412's. This is not every chip only some. 

As the chip and circuit board get below -30C the current limit will no longer be what it is set to. It will begin chopping at half of the set limit and paired with the fact we are PWMing the Phase pins the current is chopped even less. 

So if the current is set to 1.9A (150K ohm resistor) the DRV8412 will chop around 1A. This is consistent on all the "bad" chips. 

Is there some EERATA on this? Or an explanation of why is happening? 

In order to continue to use the chips we have to set the current limit higher than we feel is safe or needed. 

Any information would be helpful. 

Thank you

  • 0
    TI__Guru** 114905 points
    Hi Sheldon,

    We are not aware of any issues like you described.

    How many devices exhibit this behavior? How many devices do not?
    If you move the suspect device to a good board, does the behavior follow the device?
    If you move a good device to a suspect board, does the behavior continue on the suspect board?
  • 0 in reply to Rick Duncan
    Prodigy 225 points
    I don't have a count of devices with or without. It has happened on three different designs pretty consistently over the last couple years.

    We have taken a board that doesn't work and swapped out the DRV8412 and it will function after swapping the part.
    Have never taken a bad chip and moved boards as this could add more issues ( heat from removing the part)
  • 0 in reply to SheldonTT
    TI__Guru** 114905 points
    Hi Sheldon,

    Swapping devices from good to bad and bad to good is known as an A-B-A swap. Doing the swap eliminates some variables and is a standard question if returning devices.

    We have seen problems in the past at cold temperatures or high humidity that are not associated with the device.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Sheldon,

    We have not heard from you in some time, and are assuming your issue has been resolved. If it has not, please reply to this thread.
    If the thread is locked, please select "+Ask a related question" at the top right.
  • 0 in reply to Rick Duncan
    Prodigy 225 points

    I am trying to get more info on the issue. It is not resolved. I just do not have enough information to prove to you that the issue is in your chip. I will reply when I have that information. 

  • 0 in reply to Rick Duncan
    Prodigy 10 points

    Hi,

    I have seen this issue on the manufacturing side.  I have performed the A-B-A swap as requested and found that it does follow the IC.  I have also viewed the issue on several brand new boards,  hit them with cold spray, to confirm the issue.  And, then replaced the part, and then saw the problem go away.  We use conformal coat on the devices, and still see the issue, I do not believe this is a humidity issue.  I have never seen the issue follow the PCB, but the IC.  I have sent a failing component out to x-ray and did not see any obvious damage to the part.  As per quantities, I would estimate 1 in 60 have this issue, but it will take more time to substantiate a firm number.

    Ocey

    Manufacturing Test Engineer

  • 0 in reply to Ocey Grant
    TI__Guru** 114905 points

    Hi Ocey,

    Thank you for running the experiment. Based on the results, it appears there could be something wrong with the device.

    Please make arrangements to return the device through the company you purchased the devices.

    When providing information, please provide the information needed to duplicate the failure such as PVDD voltage, inputs, OC adjust values, loads, etc.

    Also please provide as markings on the top of the package. This will allow to begin our investigation.

  • 0 in reply to Rick Duncan
    Prodigy 10 points

    Hi Rick,

    I have 2 parts that exhibit the failure Ocey has described. We don't purchase the parts directly because we us a contract manufacturer(Precision Technology Inc. Plano Texas) to assemble our boards.

    May I send them directly?

    Thanks,

    Dale Weaver

  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points

    Hi Ocey,

    For now, I will mark the thread as TI thinks resolved for tracking. Feel free to reply to the thread if unlock or select "+ Ask a related question" if locked.

  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points

    Hi Dale and Ocey,

    Please work through your CM, who may have to work through their distributor for returns.

    The return procedure link is: http://www.ti.com/support-quality/resources/customer-returns.html