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BQ75614EVM-021: Stacking BQ75614EVMs

Ray
Prodigy 170 points

Part Number: BQ75614EVM-021
Other Parts Discussed in Thread: BQ79616

Is it possible to stack 2 (or more) BQ75614EVM modules to get a higher voltage BMS?  See below drawing. By stacking I mean tying the load lines in series.  Will the below configuration work using 3 BQ75614EVM-021 boards?

If I was starting from scratch and wanted to use your EVAL boards for a proof of concept, whch EVAL board(s) would you recommend I use to build a >16 cell BMS?

  • 0
    TI__Intellectual 1880 points

    Hi Ray,

    I recommend taking a look at the BQ79656 which is a similar device to the BQ75614 but supports up to 16 channels and supports stacked communications that would allow for a single MCU/CAN connection to talk to all devices.

    Regards,

    Geoff

  • +1 in reply to Geoffrey Grimmer
    Prodigy 170 points

    Hello Geoffrey,

    Thank you for the BQ79656 suggestion.  I've looked at that and it appears to me that would lead to a 2 SKU solution.  One SKU for a BQ79656 based BMS circuit board (for the base/bottom battery pack with micro) and a second SKU for a BQ7961x based BMS circuit board (for the upper battery packs without micros).  Production likes less SKUs not more so I am looking for a 1, fits all SKU solution.  I am not new to electronics design but this is the first BMS I am designing so I what to get the opinion of the experts before I spend a lot of time and money on this design concept that could possibly just end up in smoke... literally  So, in your opinion, will 3 BQ75614EVM-021 boards function as a BMS for a 48 cell battery pack?  Any technical downsides or safety issues?  You can assume that all MCUs, CANs, and Main Controller all share the same isolated ground as the 12V.  Thanks in advance.

    Ray

  • +1 in reply to Ray
    TI__Intellectual 1880 points

    Hi Ray,

    I don't see why the BQ75614 solution that you are proposing would not work.

    For the BQ79656 solution that I was proposing you can still use a 1SKU solution comprised entirely of BQ79656 devices. In typical applications we propose BQ79656 paired with a stack of BQ79616 as the most common setup includes a single current sense application.

    Either a setup with 3 BQ75614s or 3 BQ79656s should work for your case. The biggest difference will simply be how you want to communicate with the devices.

    Regards,

    Geoff