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BQ40Z50: NORMAL Mode

Ryo Akashi
Genius 9470 points
Part Number: BQ40Z50

Hello experts,

I have question for BQ40Z50 NORMAL Mode.
In Technical reference manual (sluua43a) page 42, there is description of 
"In NORMAL mode, the device takes voltage, current, and temperature readings every 250 ms, performs protection and gauging calculations, updates SBS data, and makes status decisions at 1-s intervals."
In my understanding, we take 4 voltage data in 1-second.
For example, we take Va, Vb, Vc, Vd (Va>Vb>Vc>Vd).
These data are used for status decisions by comparing with threshold value.
But I'm not clear how these data are used. 
In this case, which data is used for comparing with threshold value?
Va (Max value) or Vd (min value) or (Va+Vb+Vc+Vd)/4 (average value)?
I would appreciate if you would give me the detail of taking data treating in NORMAL Mode.
Thanks and best regards,
Ryo Akashi
  • 0
    TI__Genius 12215 points

    Hi, Ryo

        The value read from the AFE is averaged overtime with a filter factor consistently, then on each 1-s interval, the gauge read this filtered value to make decision by comparing the max and min of the filtered cell voltages with the thresholds set in data flash

       

  • 0 in reply to Steven Yao
    TI__Genius 9470 points

    Hi Steven,

    Thank you for your reply.

    Let me confirm my understanding.

    I thought the value which is read from AFE every 250 ms are averaged in 1-s,  so the averaged value is one value.

    It is compared with thresholds on each 1-s intervals.

    You mentioned " the gauge read this filtered value to make decision by comparing the max and min of the filtered cell voltages with the thresholds set in data flash"

    What is the max and min of filtered cell voltage? Filtered cell voltage is different from averaged value?
    Thanks and best regards,
    Ryo Akashi
  • 0 in reply to Ryo Akashi
    TI__Genius 12215 points

    Ryo

        The algorithm used for filter the voltage is the convoluted result of actual voltage read from AFE and the output of IIR filter. the time domain is from 0 to present. It is not the averaged value of 4 samples within 1s interval.

         So each cell connected in series in the battery pack has it filtered voltage at any particular time point, The max and min value are the filtered cell voltages among the 3 to 4 cells in series in the battery pack

  • 0 in reply to Steven Yao
    TI__Genius 9470 points

    Hi Steven,

    Thank you for your reply.

    I misunderstood about averaged value.

    Actual voltage read from AFE is taken every 250-ms. Also, there is filtered output. (IIR means Infinite Impulse Response?).

    These two data are convoluted and the result (the time domain is from 0 to present) will be compared at 1-s intervals to make status decisions. 

    Is it correct?

    I understand the max and min value are the filtered voltage for each cells. 

    Thanks and best regards,

    Ryo Akashi

  • 0 in reply to Ryo Akashi
    TI__Mastermind 24870 points

    Hello Akashi-san,

    What is the question you are trying to answer? We do internal filtering on the AFE raw output. That is the only thing we can share.

  • 0 in reply to Kang Kang
    TI__Genius 9470 points

    Hello Kang-san,

    My question was how does this device use the data to make status decision.

    I understood that this device does internal filtering on the AFE raw output and that is the only thing we can share.

    Let me ask one more question. Customer wants to know the period of exceeding threshold.

    When the filtered value exceed the threshold first time,

    -It is treated as the starting point (0 seconds) 

    -It is treated as exceeding the threshold for the past 1 second

    Which is correct?

    I would appreciate if you would give me comment.

    Thanks and best regards,

    Ryo Akashi

  • 0 in reply to Ryo Akashi
    TI__Genius 12215 points

    When the filtered value exceeds the threshold first time, a counter will start from 0 to count on the seconds elapsed from now on, if the counter exceeds the specified delay time, the relevant protection status bit will set. Actions will be taken per actual configurations in data flash

  • 0 in reply to Steven Yao
    TI__Genius 9470 points

    Hello Steven,

    Thank you very much for your quick reply.

    I understand.

    Thanks and best regards,

    Ryo Akashi