• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 113 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.

BQ77216: work with a BQ769x2 device

Hang Zheng
Prodigy 10 points
Part Number: BQ77216
Other Parts Discussed in Thread: BQ76942

HI

According to the datasheet of BQ77216, when working with a BQ769x2 device, the LOOPSLOW setting of the BQ769x2 device should be set to 0x11 to ensure the BQ77216 VOW spec is met.
What happens if the LOOPSLOW of the BQ769x2 device is set to 0x00 when bq7721609 is working with BQ769x2 device?Will the COUT and DOUT pins go from an inactive to active state？What's the probability of it happening？
  • 0
    TI__Genius 15840 points

    Hi Hang,

    When the bq769x2 takes a cell voltage measurement, it pulls a small current into the corresponding pin. When the bq77216 measures open wire, it also pulls a small current into the pin. If both devices are taking measurements at the same time, there is a chance that the bq77216 will falsely detect an OW and trigger the protection fault. The chances of this can be mitigated by setting LOOPSLOW to 0x11 or by using a version of the bq77216 with OW detection disabled.

    Regards,

    Max Verboncoeur

  • 0 in reply to Maxwell Verboncoeur
    Prodigy 10 points

    Hi Max,

    When LOOPSLOW is 0x00, the sampling period of the BQ76942 is 45ms and the OW detection period of the BQ77216 is 128ms. At a certain point in time, they both measure a cell simultaneously, triggering an OW fault in the BQ77216. When the next OW detection period arrives, the BQ76942 will not be measuring this cell, and the OW fault timer will be reset,the COUT and DOUT pins will not go from inactive to active state.

    Furthermore，between the cell and the chip, both the QB769x2 and BQ77216 have their own RC filter networks. I think that the resistances of the filter network can prevent them from affecting each other during operation, and the OW fault of the BQ77216 should not be triggered.

    Regards

  • 0 in reply to Hang Zheng
    TI__Genius 15840 points

    Hi Hang,

    I agree, this does sound like it should be fine as long as the RC networks are separate for each device. I'm checking with someone on the team who may know why the datasheet indicates otherwise and I'll get back to you once I have heard back from them.

    Regards,

    Max Verboncoeur

  • +1 in reply to Maxwell Verboncoeur
    TI__Genius 15840 points

    Hi Hang,

    I checked with the team and we're not sure why the datasheet says to set LOOPSLOW to 0x11. If the RC filters are separate, then the OW current sink and the measurements should not affect each other, so it should be okay to set LOOPSLOW to 0x00.

    Regards,

    Max Verboncoeur