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BQ25887: Overcharge and discharge protection?

JD Peiffer
Prodigy 130 points
Part Number: BQ25887

Hi,

The BQ25887 looks like a great charger for 2S batteries. It is not clear to me if it stops charging once the cells reach their target voltage--is there overcharge protection in this or discharge protection?

Thanks,

JD

  • 0
    TI__Genius 10385 points

    JD,

    The charger device automatically terminates the charging cycle once the charge termination threshold is reached. At the end of the charge cycle the charger operates CV mode gradually reducing charging current until the termination current is reached. At this point charging stops and will remain stopped until VCELL_RECHG threshold value is reached. This threshold voltage is reached as the battery discharges and the cell voltage falls below the threshold. 

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Prodigy 130 points

    Thanks Ricardo,

    This is very informative. What are the specified threshold voltages? Are they specified in the data sheet?

    JD

  • 0 in reply to JD Peiffer
    TI__Genius 10385 points

    JD,

    The recharge threshold is programmable via I2C as is the voltage regulation threshold for CV mode. The voltage regulation threshold (VCELLREG) is programmed by REG00[7:0]. The recharge threshold (VCELL_RECHG) is programmed by REG06[1:0] and based on the your VCELLREG value. For example, the default setting is 100mV for VCELL_RECHG, so charging will resume when one of your cells falls 100mV below your VCELLREG value. These settings are described in the register map section of the datasheet (section 8.5)

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Prodigy 130 points

    Thank you for the timely reply Ricardo; this makes me feel much better about purchasing this product.

    Do you have any Eagle files that I could use to incorporate this into my design?

    JD

  • 0 in reply to JD Peiffer
    TI__Genius 10385 points

    JD,

    Unfortunately I could provide only you with an Altium layout file.

    Sorry for the inconvenience,

    Ricardo