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BQ2980: BQ2980 OCD/SCD recovery

Part Number: BQ2980

Hi team,

How to recovery BQ2980 from OCD or SCD when the discharge load can't be removed?

  • Hi Yuting,

    The OCD/SCD recovery is described in table 8-1 of the BQ2980 data sheet.   The charger would need to raise the voltage of the PACK back to near normal.  If the OCD or SCD condition remains the charger may not be able to cause recovery.  If the load remains at a fault level but the charger can overcome it, when the charger is removed the BQ2980 will go back to OCD..

  • Hi WM,

    So if the load can't be removed, there is not 100% successful recovery method from OCD/SCD. Right?

    What does the internal current sink between the PACK and VDD pins work?

  • Hi Yuting,

    It depends on the characteristic of your non-removable load, but basically right, OCD/SCD probably can't recover every time with load attached.

    Assume your system has a BQ298000 with a10 mOhm sense resistor and draws a normal load of 100 mA, 1 mV does not cause an overcurrent.  But if it goes into some operating mode which draws 900 mA with 9 mV and remains, it crosses the 8 mV OCD threshold and will have an OCD fault.  The 900 mA load would pull the PACK+ and PACK pin voltages down.  The part will enable the IPACK-VDD current sink of 8 to 24 uA.  If your load that can't be removed (residual load) looks like a high impedance or maybe just a capacitance long enough for the part to pull up PACK, the part will recover from OCD.  If the system retains a DC load that prevents the PACK voltage from rising within 400 mV of trhe BAT, it will likely consume the 24 uA of current from the PACK pin and the part will not recover.  A charger would be needed to overcome the residual load.