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BQ40Z80: Built-in flash specifications

Masashi Mineda
Expert 1205 points
Part Number: BQ40Z80

Dear Sirs and Madams,

We are considering BQ40Z80.

During SMBus communication, a NACK may be returned from the BQ40Z80, and when I investigated the reason for the NACK using TRM, I found that the flash was "BUSY".

I understand that the reason why the flash is busy is updating parameters (Qmax, Ra tables, etc.) during the learning cycle.

I confirmed for the flash characteristics in the BQ40Z80 datasheet, but only "Word programming time", "Mass-erase time", and "Page-erase time" are listed.

I think flash basically performs row programming, but could you tell us about the time required for row programming (erase and program) and number of bytes in row?

/* BQ40Z80 datasheet URL */

https://www.ti.com/lit/ds/symlink/bq40z80.pdf?ts=1703658183430&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252Fja-jp%252FBQ40Z80%253FkeyMatch%253DBQ40Z80%2526tisearch%253Dsearch-everything%2526usecase%253DGPN

Regards,

MM

  • +1
    TI__Guru** 105770 points

    Hello MM,

    Generally you should wait 100ms between flash writes if you are performing them. As you mention the gauge will perform flash writes itself from Qmax, Ra, and lifetime data, as well as others which are command induced like gauge enable. If clock stretching is enabled the gauge should still respond unless there is a large flash write occurring from lfietime data.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Expert 1205 points

    Hi Wyatt,

    I understood that writing to flash is row writing from your answer.

    I thought it would be a good idea to reduce the frequency of SMBus accesses.

    Regards,

    MM

  • 0 in reply to Masashi Mineda
    TI__Guru** 105770 points

    Hello MM,

    Generally around 70 SMBus transactions per second is what we recommend for a maximum, communication has high priority in the gauge so it can cause delays in other operations if communication is continuous with no rests.

    Sincerely,

    Wyatt Keller