• State Resolved
  • Locked Locked
  • Replies 9 replies
  • Subscribers 30 subscribers
  • Views 443 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.

DRV5011: Phenomenon in which an abnormal signal is seen in the output of the DRV5011

Conor
Mastermind 9870 points
Part Number: DRV5011

Hi,

I'm using the DRV5011ADDBZT to drive a motor, but I've observed an abnormal signal in the IC's output.

【Phenomenon】
When the motor is controlled at 500rpm, the following waveform is observed in the IC output once every few minutes.

CH1-3: DRV5011 output
CH4: Power supply voltage Vcc

Similar waveforms were observed for all of CH1, CH2, and CH3. On the other hand, we measured the rotation speed up to 1500rpm for 1h, but this phenomenon was not observed even once.


[Regarding the motor used]
As shown below, it is an outer rotor motor with a diameter of about 30mm. It is a magnetized rotor with 4 pole pairs per rotation.


The rotor bearing is fixed at a fixed position and pressurized, and it is thought that there is almost no mechanical shake. As a reference, the graph below shows the magnetic flux measured at the position equivalent to the Hall sensor.


Please let me know what could be the reason for this and how to prevent it from happening.

Thanks,

Astro

  • 0
    TI__Mastermind 24105 points

    Hello Astro,

    Thanks for considering to use Texas Instruments.  We have identified an issue with some of our old material and that could be related to this.  Could you provide me a picture of the top of the device or tell me what letters and and dashes you see on top.  If its not readable, can you provide me a picture of the tape or reel labeling?

  • 0 in reply to Patrick Simmons
    Mastermind 9870 points

    Hi, Patrick

    Below is a picture from the top of the package.


    The printed characters are "1AD".

    Thanks,

    Astro

  • 0 in reply to Conor
    TI__Mastermind 24105 points

    Hey Astro,

    Thank you for providing that.  I am still waiting on a response from my team as to whether we think this is a material issue or something we need to debug at the system level. Will let you know as soon as I get an update from my team.

  • 0 in reply to Patrick Simmons
    Mastermind 9870 points

    Hi, Patrick

    OK, I am waiting for your reply!

    Thanks,

    Astro

  • +1 in reply to Conor
    TI__Mastermind 24105 points

    Hello Astro,

    From the details you have provided: date-codes, supply decoupling cap placement, clean (low noise) oscilloscope signals, and glitch duration, I suspect this is an issue with the material you purchased.  I would encourage you to fill out a failure analysis here, which will confirm if the issue is from bad material and not something in your system.  Alternatively, if you prefer to gamble, you could just request product replacement. In the interim, can you confirm you do not have any magnets moving past the devices or any high current traces aside from your motor traces that periodically turn on near these devices?

  • 0 in reply to Patrick Simmons
    Mastermind 9870 points

    Hi, Patrick

    Question
    1. Is this phenomenon a defect that occurs in a certain lot?
    2. is it correct to understand that this problem has been resolved in the chips currently being shipped from TI?
    3. Since it is an issue with older materials, is it possible that other devices will have the same issue?
    4. The problem is that the pulse is output at an unintended timing. I want to know if the pulse width is different for different ICs.
    5. In our experiments, the strength of the interlinking magnetic flux tends to determine whether or not this defect occurs. This phenomenon does not occur by increasing the rotation speed of the motor. Do you have any information that this problem occurs where there is little interlinking magnetic flux?

    The reason why I asked questions 3 to 5 (defect mechanism) is that if this defect can be tolerated in the application, we are considering continuing to use the IC we have.
    I am asking this question because I currently have 300 ICs with the same printing, and I am considering whether to continue using them or to replace them. If the content is difficult to answer, I would appreciate it if you could answer by private message.

    Thanks,

    Astro

  • 0 in reply to Conor
    TI__Mastermind 24105 points

    Hello Astro,

    We identified a 8us glitch in a previous version of the silicon and it has been fixed in the newer version of silicon.  If all your devices are from the same order with the devices you have observed the glitch in and have the same date code markings, then all should have this issue.  Increasing motor speed should not be an issue for the device.  This issue that is in the previous version of the silicon is a logic path delay mismatch between some internal circuit paths that activate the hysteresis

  • 0 in reply to Patrick Simmons
    Mastermind 9870 points

    Hi, Patrick

    Thank you for answering my question.

    >All devices should have this issue if they are on the same order and have the same date code as the device with this issue.

    Is it possible to judge whether or not this problem occurs by the IC printing? Does it mean that it occurs when only "1AD" is printed?
    Also, does "All devices" indicate a different model number? I would like to know which model number it specifically occurs in.

     

    >We identified a 8us glitch in a previous version of the silicon and it has been fixed in the newer version of silicon. 

    Is the 8us pulse width different for each IC? Or will all devices output the same pulse width?

     　

    >Increasing motor speed should not be an issue for the device. 

    In our experiments, the pulse was not output when the motor speed was increased. Is this pulse output problem really unrelated to motor speed?

    Thanks,

    Astro

  • 0 in reply to Conor
    TI__Mastermind 24105 points

    Hello Astro,

    “All devices” refers to all DRV5011 devices with the same date code.  All DRV5011ADDBZT are marked with “1AD”.  I will need to confirm with my team, but I do not think it matter if it is in the SOT-23, DSBGA, X2SON, or TO-92 package variant.

    The glitch is 8us +- tolerance.  Are you observing significantly longer or significantly shorter glitches in other DRV5011 devices?

    For increased motor speed, did you test over several hours?