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BQ78350: BQ78350+BQ76930 abnormal power consumption

Part Number: BQ78350
Other Parts Discussed in Thread: BQ76930, BQ76200


The customer design with BQ78350+BQ76930 with 8 series cells. They found the 7th cell have 0.7mA current consumption.

When removed the cell balance circuit still have 0.7mA current.

Attached the schematic for your reference.


Please give some suggestions.



  • Hi Star,

    I am not sure why they are seeing 0.7mA on Cell 7 - are they measuring the current across by looking at the voltage drop on RF7? Have they tried replacing the IC?

    I do see a few things in the schematic that may cause additional problems:

    • Pin 11 and 12 of the device should connect directly to the CAP2 pin (should not use 1k resistors).
    • It is good to use a filter capacitor on the Alert pin in addition to the pull-down resistor. This can prevent false ALERT_OVRD protection triggers due to noise. See the BQ769x0 schematic video for more information: 
    • The CAP1 and CAP2 pins should not connect to additional circuitry. It looks like CAP1 is being used to drive the base of Q1 to enable LEDs.
    • The BQ76930 is driving several parallel protection FETs. It is recommended to use individual gate resistors on each FET to prevent oscillations which is a common issue when controlling many FETs in parallel. Also, since many FETs are in parallel, a FET driver like the BQ76200 may be needed. These resources may be helpful:

    Best regards,