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BQ2970: LiSOCl2 Primary Cell Reverse Current Protection

Jim G
Intellectual 685 points
Part Number: BQ2970

I am searching for a solution to prevent charging of a primary LiSOCl2 cell. According to the manufacturer I should keep charge (reverse) current at or under 10uA.

I found this old post on the forum which suggests BQ2970 as a protection/monitoring IC for a primary LiSOCl2 cell, but I do not believe this

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/863832/battery-protection-for-lisocl2-lithium-battery-ls-14250-from-saft

I suppose I could select a device with the lowest OCC threshold (BQ29737 based on the table is -50mV), but this does not protect me from a specific current.

I could add a series resistor here to modify the charge current difference, but would prefer not to lose the voltage drop under normal use.

Are there any other protection IC's which might be well suited to prevent reverse charging on a primary LiSOCl2 cell?

  • +1
    TI__Mastermind 25880 points

    Hi Jim,

    If you don't need OCD or SCD protections, then using a resistor between V- and VSS to adjust the OCC threshold would work. If you do need them then you may be able parallel two bq297x's, one for the discharge current protections and the other for the charge current protections (the voltage protections could be controlled by either).

    You may also be able to replace the CHG FET with a Schottky diode to block any charge current.

    Regards,

    Max Verboncoeur