• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 2 answers
  • Subscribers 64 subscribers
  • Views 308 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.

BQ76PL455A: All cell conversion time

K. Sasaki14
Guru 10200 points
Part Number: BQ76PL455A

All cell conversion time is in 2.4ms on the datasheet P.1.

How can I calculate this time?

Best Regards,
Kohei Sasaki

  • 0
    TI__Intellectual 2520 points

    Hi Kohei,

    Everything is in DS.

    Please look into details at section 7.3.3.2.

    (60+12.6x7)x16

    Andy

  • 0
    TI__Genius 17370 points
    Hi Kohei,

    The recommended settings for best accuracy are:

    - 16 cell channels

    - 390pF OUT filter cap

    - AFE_PCTRL = 1 (causes 100us for ADC power up)

    - Cell ADC sample period = 60us

    - Cell ADC sample period for oversamples = 12.6us,

    - Staying on a cell channel to oversample

    - AUX ADC sample period = 12.6us

    - 8x oversampling of CELL and AUX channels

    So the amount of time to sample all channels = 100us + (60us + (12.6us x 7)) x 16 = ~2.47ms.
    If you require a shorter sample time, you can adjust some of these values to try to get there. For example, you could change to 4x oversampling and reach ~1.66ms.

    Best Regards,

    Taylor
  • 0 in reply to Taylor Vogt
    Guru 10200 points

    Taylor-san, Andy-san,

    Thank you for your answer.

    I understood your recommended setting.

    Voltage reading accuracy becomes worse by following setting, right?

    - Set CMD_OVS_CYCLE = 1

    - Reduce ADC sample period

    - Reduce oversampling times

    Best Regards,
    Kohei Sasaki

  • 0 in reply to K. Sasaki14
    TI__Intellectual 2520 points

    Hi Kohei,

    CMD_OVS_Cycle setting will impact sync between cells and overall conversion time for all channels;

    OVS will not impact accuracy but noise suppression;

    If out cap is 390nf, then use our recommended setting for period parameters.

    Thanks!

    Andy

  • 0 in reply to Andy Li55
    Guru 10200 points
    Andy-san,

    Could you provide optimal OUT1 cap value if we want to change period parameter?
    And in that case, can we get EC table accuracy?


    Best Regrads,
    Kohei Sasaki
  • 0 in reply to K. Sasaki14
    TI__Intellectual 2520 points

    Kohei,

    390pf is our recommendation. If you use other values, it is your responsibility to validate it.

    There are still some information in EVM user guide. You can check.

    Thanks!

    Andy