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BQ76940: Hardware issue on 15S BMS with fuel guage

Part Number: BQ76940
Other Parts Discussed in Thread: BQ78350, EV2400, BQ78350-R1

Greetings,

We are using the bq7694003 as AFE , bq78350 as fuel guage IC and EV2400 from TI.Final output is viewed in SMBus.

There are some hardware issues due to which the REGOUT, SCL, SDA are not in the range of recommended operating voltage.they are 1.8V which should be min 2.5V.

Can you please suggest the testing procedure for to solve this hardware issue.

Regards,

Parimala.

  • Greetings,

    This is continuation for the above conversation.Unable to read correct cell voltages,which are over and under voltages on the board. But,at the cells the voltage is nominal which is 3.5V.

    Regards,

    Parimala.

  • Hi Parimala,

    Please note that the BMS engineers are presenting this week during our yearly BMS Deep Dive in Dallas and may not be able to answer quickly to your question. Thank you for your understanding!

    Please check out more information about this event here in case you want to join next year.

  • Hi Parimala,

    These voltages are not correct - the REGOUT pin should be 3.3V for the BQ7694003. The BQ78350-R1 needs a 2.5V supply connected to VCC.

    If you look at Table 6 (Device comparison table) in the BQ769x0 datasheet, you can see that BQ7694000 or BQ7694001 are the correct device numbers for the 2.5V REGOUT. Using a REGOUT that is too high can damage the BQ78350-R1 device. 

    Best regards,

    Matt