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BQ25887: customer want to use BQ25887 to replace BQ25883, does the cell balance can be disable?

Part Number: BQ25887
Other Parts Discussed in Thread: BQ25883,

Hi Expert,

customer want to use BQ25887 to replace BQ25883 on mass production project due to shortage, does the cell balance can be disable?

if set the cell balance CB_AUTO_EN, does the MID/CBSET can be floating? does the charging function can work normally?

  • Hi Anderson,

    MID/CBSET cannot be left floating but CB can be disabled.  Keep in mind 887 does not have a SYS output like 883 so the system load will have to connect directly to the battery.

    Regards,

    Jeff

  • Hi Jeff,

    thanks for your reply, to further confirm:

    1. how to disable CB, does set  the CB_AUTO_EN to disable ?

    2. customer's battery does not have lead out the MID point, if MID/CBSET can't be left floating, do you have any suggestion?

        how about using resistor divider to get the half voltage from the battery package? in this case can  the charging function work normally? does it have any side effect ?

    3. well noted the sys difference, we are trying to find workaround solution.

    Thanks.

    Anderson

     

  • Hi Anderson,

    Regarding 1, yes.

    Regarding 2, your resistor divider idea will work.  We have not tested with MID and CBSET floating.  If the ADC functions correctly to read the total battery voltage, then leaving them floating might be okay.  Unfortunately, we are all either on holiday or working remotely and cannot test in the lab at the moment.

    Regards,

    Jeff 

  • Hi Anderson,

    I checked with the engineer who supports this product and he confirms that the device regulates the cell voltage in REG00, not battery voltage. The top cell voltage is basically a calculation of VBAT – VCELL(bottom cell) as measured at MID. So, MID cannot be left floating.  

    Regards,

    Jeff