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BQ40Z50-R2: BQ40Z50-R3 System Design of Back EMF

Star Xu
Genius 9645 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50

Hi

The customer design with BQ40Z50, 4S1P battery pack, fully charged 17.6V.

They use the 4-axis motor with blades to output the maximum speed and then quickly reduce the speed, the system will recover immediately after power failure.

a. Before each test, use LT_RESET to clear the Lifetimes data, test the above operations, check the Lifetimes data after the test, and there is no relevant protection data;

b. Short circuit CHG-FET, DSG-FET (mos is not controlled by fuel gauge CHG, DSG), test the above operations, the system does not appear power failure;

It is now suspected that the BQ40Z50-R3 may have reset under the counter electromotive force.

Attached the .gg file and schematic.

bat.gg.csv

Please give some suggestions.

Thanks

Star

  • 0
    TI__Guru** 105740 points

    Hello Star,

    From the schematic snippet it looks like the CHG and DSG FETs are controlled by the gauge, if you have some external circuitry that is forcing voltage on the CHA and DSG nodes you may be forcing a brownout condition on the gauge since the charge pumps can consume a lot of current and it could drain the PBI capacitor.

    Sincerely,

    Wyatt Keller