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BQ40Z50: Simplifying a BQ7692000 + BQ78350-R1 design

Part Number: BQ40Z50
Other Parts Discussed in Thread: BQ76200, BQ24725, BQ78350-R1, BQ4050, BQ76952, BQ78350, BQSTUDIO, , BQ41Z90

Tool/software:

Hello,

I have a few prototypes of a BMS designed 6 years ago with a BQ7692000 AFE, a BQ78350-R1 companion device, a BQ76200 to drive the hi-side mosfets and a BQ24725 charger. This first design is working very well.

The product will jump from prototype to production state. I would like to optimize the BMS. No particular cost limitation, but it would be nice to shrink the design to spare some cm² on the PCB.

The battery is based on 18650 Li-ion cells, 4s2p.

I need :

- A SMB bus responding to SBS command (need to retrieve battery voltage / current / rsoc and basic info from a linux host)

- A 2A smart charger 

- Full protections with top-side mosfets

- External cell balancing

- ... and a design smaller than the actual

BQ4050 and BQ40Z50 seems to be the perfect devices to replace the trio (BQ7692000 + BQ78350-R1 + BQ76200). I will keep the BQ76952 charger. Does someone approve / disapprove this choice ?

I don't know if I need the Z version. BQ4050 gauge is based on CEDV, like my actual BQ78350. The gauge precision is good enough. 

Pros for BQ4050  : 

- Less expensive (but I'm not looking for a 2$ economy)

- Probably more easier to calibrate / setup ? (I'm not familiar with the impedance track algorithm)

Pros for BQ40Z50

- More precise (probably more than needed)

- Probably a little bit more easy to buy (my favorite distributor only stocks the Z version)

Feel free to comment

Thank you

  • Hello Nicholas,

    The BQ4050 and BQ40Z50 would work for you product and a I would recommend the BQ40Z50 over the BQ4050 due to it using the Impedance tracking technology over CEDV technology. However there is a new TI battery gauge that has been released that I would ultimately push for BQ41Z90. It seems to fit your application however the external cell balancing can be place on any of the battery gauges due to it being it own system. Another note all three of these battery gauge uses the same software, BQStudio, and have the same steps from design to finish product.

    BQ41Z90:
    https://www.ti.com/product/BQ41Z90