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BQ79616-Q1: Why we need BQ79600 as the communication device between BQ79616-Q1 and MCU

Miles Li1
Intellectual 1640 points
Part Number: BQ79616-Q1
Other Parts Discussed in Thread: BQ79616, BQ79600-Q1

Team,

I have found that there is UART interface in BQ79616, and why we need to add BQ79600 between BQ79616 and MCU?

What is the advantage?

Wish to get your reply, thanks!

  • 0
    TI__Genius 9301 points

    Hi Miles, 

    In a large stack of batteries, having the BQ79600-Q1 communication bridge between the MCU and the battery monitor devices allows you to keep the BMU (Low voltage system) isolated from the CMU (high voltage battery stack) as shows in the "Simplified System Diagram" in the BQ79600-Q1 datasheet.

    Please notice BQ79600-Q1 is able to communicate with the MCU using either SPI or UART (BQ79616 doesn't support SPI communication to the MCU. It also has a feature (automatic host wakeup) when using ring architecture that allows the system to be put in a low power mode while still monitoring faults. See more details in sections 7.3.4 "INH/Reverse Wakeup" and 7.3.5 Sniff Detector" in the device datasheet.

    Best regards,

    Leslie

  • 0 in reply to Leslie Marquez
    TI__Intellectual 1640 points

    Team,

    Thanks for your reply. But based on your comments, I have further questions：

       As you says, BQ79600 could keep the BMU (Low voltage system) isolated from the CMU (high voltage battery stack), but it still need transformer or cap for isolation. So, as BQ79616 could support UART interface, we could only add one ISO774x to communicate directly with MCU. 

     As result, if use UART communication, is it no need for BQ79600?

  • 0 in reply to Miles Li1
    TI__Genius 9301 points

    Hi Miles,

    Digital isolation is possible but it forces the BQ79616 to be very closed to MCU given UART is not differential line. BQ79600 uses differential communication between the BQ79600 and the BQ79616, which allows the BMU (low voltage) and CMC (high voltage) to be a few meters away. 

    Regards,

    Leslie