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Original question:

TIDA-00792: Reduced cell count

TIDA-00792: using fewer cells

Jonathan Lerch
Prodigy 25 points
Part Number: TIDA-00792
Other Parts Discussed in Thread: BQ76920, BQ76940

Dear Sir,

we are looking for a battery management system for lithium-iron phosphate batteries.

We like the reference design TIDA-00792 very much.

However, we need a nominal voltage of 12V with only four cells in series.

Can we use it for this application or would you recommend another one?

Best regards,

Jonathan

  • 0
    TI__Guru* 77283 points

    Hi Jonathan,

    Sure, you should be able to follow this reference design but use the BQ76920 (3-5S device) instead of the BQ76940. These devices share the same datasheet.

    See Table 24 in the datasheet for instructions on connecting 4 cells to the BQ76920. I also recommend watching this video to help with creating your schematic: https://training.ti.com/how-create-schematic-bq76920-bq76930-and-bq76940

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 25 points

    Hi again,

    thank you. This helped us a lot. Just one more question...

    Can we also use the same PCB in this case? It should still fit right? So we just have to change or leave some parts out during the assembly?

    Otherwise if we have to design our own PCB; are there any existing EAGLE-files available we could adapt?

    Best regards

    Jonathan

  • 0 in reply to Jonathan Lerch
    TI__Guru* 77283 points

    Hi Jonathan,

    The BQ76920 does not have the exact same package footprint of the BQ76940. There are also more components required for the BQ76940 to support higher cell count, so a board using the BQ76920 should be significantly less complex.

    Unfortunately we do not have a reference design for the BQ76920. If you send me an E2E friend request, I can send you a private message with the EVM design files (I do not know if these are EAGLE though). However, the EVM has a much more complex schematic to enable all types of evaluation so it is not the best example to follow.

    Best regards,

    Matt