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BQ76940 - BQ78350 - BQ76200 Monitor system and charger

Rodrigo Lorenzo Leal
Prodigy 90 points
Other Parts Discussed in Thread: BQ76200, BQ76940, BQ78350-R1

I'm currently designing a battery powered system that will use a 12 cell LiFePO4 (38.4 V) battery pack. This is the model of the single cell

Ideally I want to build a complete circuit board that manages, monitors, protects and charges the battery. The idea is for the pack to report it's current state (SOC, SOH, current charging and discharging conditions, etc) to an external host CPU

Analyzing different alternatives I found that the combination of the BQ76940 and the BQ78350 is a great choice because they fit my requirements, can work seamlessly with each other and can communicate with my host MCU via SMBus. 

I did some more research and found the BQ76200, and in particular this note and this note. 

My question in particular is, can the set up in the Figure 1  in the slva729a document (Page 4) is suitable for this application? Do I have to use another IC to work as charger? 

I searched for chargers IC but found that TI only offers chargers IC up to 6 cells systems (Ex BQ34618). Does the BQ76200 in the previous scheme work as charger, or do I have to add other IC (such as BQ34618) to complete the solution?

Does anyone have previous experience combining all this IC's?

Thanks beforehand

  • 0
    TI__Guru 54715 points
    Right, a solution with the bq76940, bq78350-R1 and bq76200 is expected to provide a solution to a 12 cell battery pack allowing easy communication to the gauge even when protected. The figure 1 of slva729 provides an overview with 5 cells, the larger cell count AFE would be needed of course for the 12 cell implementation. Assemble the complete schematic using the guidance in the device application notes and EVMs.
    Chargers for higher cell count packs can be more varied, I believe without specific IC to cell count correspondence. A search in the Battery Management - Chargers Forum may show a solution or the experts there would be able to provide better recommendations.