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Fault definition of LOT and DOS

Category: Datasheet/Specs
Product Number: AD2S1210

Hi ,

Could someone help me to know the fault definition of LOT and DOS.

Here is the fault bit, could you tell me how these errors are calculated?

For example, the mismatch error of D4,how to use the values ​​of sin and cos to perform calculations ?

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    •  Analog Employees 
    Apr 1, 2024 in reply to NathanT +1 suggested

    Hi  ,  .

    Thank you for your patience. AD2S1210 continuously tracks the position of the resolver in a way that the resulting error between the received input angle and the produced angle…

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  • Hello  ,

    I am currently looking into this. But may I know your specific application since you have asked about the calculations for these things?

    Thank you and regards,
    Jo

  • Hi Jo

    Are there any updates about this question? My customer has the same confusion, too.

  • Hello,  ;  .


    I am still in contact with the product owner. But I may get back to you on the 1st of April as we have holidays here starting tomorrow.

    Regards,
    Jo

  • Hi  ,  .

    Thank you for your patience. AD2S1210 continuously tracks the position of the resolver in a way that the resulting error between the received input angle and the produced angle is compared and driven to zero (0) whenever the converter is correctly tracking the input angle. LOT and DOS are fault detection feature of AD2S1210; whereas, 

    • LOT indicates that a loss of tracking (LOT) has occurred in AD2S120 when:
      • an internal error signal has exceeded the specified angular threshold.
        • threshold is defined by the user and is set by writing to the internal register, Address 0x8D.

      • the input signal exceeds the maximum tracking rate.
        • maximum tracking rate depends on the resolution defined by the user and the CLKIN frequency.

    • DOS indicates that a degradation of signal (DOS) has occurred for two (2) separate conditions:
      • If the input signal (sine or cosine) exceeds the configured DOS sine/cosine threshold
        • threshold is configured in the Address, 0x89 (DOS overrange threshold)

      • If the amplitude of the input signal mismatched the DOS sine/cosine mismatch threshold
        • threshold is configured in the Adress, 0x8A (DOS mismatch threshold)
        • difference between max and min magnitude is calculated to determine if a DOS mismatch occurs
        • min and max values are defined through Addresses, 0x8C and 0x8B

    When a fault occurs, output pins DOS and/or the LOT are taken low and the fault registers, D7 to D0, are taken high. To determine the cause of fault, you need to read fault register through Address, 0xFF. If D4 is high, then it means that the input of your system exceeds the DOS mismatch threshold you set. 


    Regards,
    Jo

  • Hi Jo,

    D4 = sin_max - cos_max > threshold

    D5 = sin_max or cos_max > threshold

    D6 = sin_min or cos_min < threshold

    Is it correct ?

  • Hello  ,

    Yes. You are correct. But for D6, it still based on the max amplitude (crest) seen. Once it is below the threshold, it is considered a LOS.

    Thank you and regards,
    Jo

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