• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 31 subscribers
  • Views 300 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.

DRV10866: Lock detection operation and Internal sampling clock flactuation

Yuto Hori
Prodigy 400 points
Part Number: DRV10866

Hi team,

Customer have a question about DRV10866 Lock Detection Functionality in the Application Report(SLVA612A ). Please answer the following.

  1. The Application Report says "If the FG signal is sampled as a static value for approximately 305 clocks of an internal sampling clock, the internal logic signals that the rotor is locked." but is it not locked unless it is detected 305 times in a row? For example, if it detect 304 times in a row and doesn't 305th time, the counter is cleared to 0. Is this understanding correct?

  2. If FG signal (rotation speed) fluctuates by 0.16% or more within 305 clocks, it doesn't lock? In other words, assuming that the internal sampling clock is constant at 101.6 Hz, it doesn't lock if the FG signal fluctuates from 101.5 Hz to 101.7 Hz within 305 clocks. Is this correct?

  3. Please provide the maximum rate of change and value at which the internal sampling clock (101.6 Hz) fluctuates during 305 clocks. For example, customer would like to know like this: "the internal sampling clock fluctuates at a maximum rate of 0.1% and it fluctuate from 101.5 Hz to 101.7 Hz."

  4. Please show the temperature characteristics of the internal sampling clock (101.6 Hz) in graph.

Your support is highly appreciated.

  • 0
    TI__Mastermind 24440 points

    Hi Yuto,

    Thank you for your questions! We will aim to provide you a response by the end of next week.

    Regards,

    Joshua

  • 0
    TI__Mastermind 24415 points
    Yuto Hori said:
    The Application Report says "If the FG signal is sampled as a static value for approximately 305 clocks of an internal sampling clock, the internal logic signals that the rotor is locked." but is it not locked unless it is detected 305 times in a row? For example, if it detect 304 times in a row and doesn't 305th time, the counter is cleared to 0. Is this understanding correct?

    Yes, your understanding is correct!

    Yuto Hori said:
    If FG signal (rotation speed) fluctuates by 0.16% or more within 305 clocks, it doesn't lock? In other words, assuming that the internal sampling clock is constant at 101.6 Hz, it doesn't lock if the FG signal fluctuates from 101.5 Hz to 101.7 Hz within 305 clocks. Is this correct?

    Device triggers lock only when FG frequency is between 101.437 Hz (101.6-0.16%) and 101.763 Hz (101.6+0.16%) 

    Yuto Hori said:
    Please provide the maximum rate of change and value at which the internal sampling clock (101.6 Hz) fluctuates during 305 clocks. For example, customer would like to know like this: "the internal sampling clock fluctuates at a maximum rate of 0.1% and it fluctuate from 101.5 Hz to 101.7 Hz."

    The internal sampling clock reference is set to approximately 101.6 Hz, with a variance of 10% at VCC 5 V room temperature.

    Yuto Hori said:
    Please show the temperature characteristics of the internal sampling clock (101.6 Hz) in graph.

    Tolerance is 10% as mentioned in previous response. 

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    TI__Prodigy 400 points

    Thank you for answering. Please allow me to add the below question.

    Vishnu Balaraj said:
    Device triggers lock only when FG frequency is between 101.437 Hz (101.6-0.16%) and 101.763 Hz (101.6+0.16%) 

    Customer also would like to know the condition for avoiding lock. Is it only when FG frequency is out of 101.437 Hz (101.6-0.16%) ~ 101.763 Hz (101.6+0.16%)? 

    Vishnu Balaraj said:
    The internal sampling clock reference is set to approximately 101.6 Hz, with a variance of 10% at VCC 5 V room temperature.

    Could it happen that the internal sampling clock(101.6Hz) flactuates by more than 10% within 305 clocks?

    They also would like to know the value change between -10°C and +85°C. Does it fluctuates by more than 10%?

  • 0 in reply to Yuto Hori
    TI__Mastermind 24415 points

    Please refer to section 2.2, 2.3 and 2.4 in the below app note for workarounds.

    App note on DRV10866 Lock detection: https://www.ti.com/lit/an/slva612a/slva612a.pdf

    Yuto Hori said:
    Could it happen that the internal sampling clock(101.6Hz) flactuates by more than 10% within 305 clocks?

    Yes, it can fluctuate at temperature and voltage corners which can add an additional 1-2% variation. 

  • 0 in reply to Vishnu Balaraj
    TI__Mastermind 24415 points

    I will close this for now, since I haven't heard a response back. If you want a follow-up, please feel free to create a new thread by clicking "Ask a related question" button located on top right of this page.