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BQ77915: Schematic Review

TI-CSC
Genius 10685 points
Part Number: BQ77915

Tool/software:

Hello E2E Experts, 

God day.

I would greatly appreciate it if you could review the attached schematic for any necessary corrections or improvements.

The schematic is attached to the next message in PDF format with the list of specifications.

Your expertise in checking this schematic would be invaluable to ensure the design meets the specified requirements. If you have any suggestions or corrections, I would be grateful for your feedback.

The specifications for the system are as follows:

Pack voltage range: 14V - 12V
Cell normal charge voltage: 4.2V
Cell cutoff voltage: 2.8V
Over-current trip point: 3.5A
Max ambient temperature: Around 40°C (Approximately 38°C inside the enclosure)
Cell configuration: Selected to provide 4.5 Ah over the system range of operation
Cell balancing: Desired with a current around 10% of termination current
Load removal for fault recovery: Required
(Recovery by connecting the charger is acceptable, as the application of the battery pack could not physically disconnect the load easily)

BMS7791501.pdf

Regards,

TI-CSC

  • 0
    TI__Mastermind 34930 points

    Hello CSC,

    Feedback:

    • R25 should be 10-MOhm
    • R30 should be 3-MOhm
      • There should be a diode in parallel to R27 and an additional in-line pin resistor.
    • Zeners across gate-source of FETs are recommended to protect the MOSFETs from transients.

    I'd recommend to see the EVM schematic for some guidance!

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    TI__Genius 10685 points

    Hello Luis,

    Good day.

    I noticed that you recommended changing resistors R25 and R30. Could you please explain why these changes are necessary and what specific properties of these resistors have been altered? Understanding the reasoning behind these adjustments will help me better apply your guidance in the future.

    Regards,

    TI-CSC

  • 0 in reply to TI-CSC
    TI__Expert 4115 points

    Hello CSC,

    Luis will be back in office tomorrow to answer your question. Thank you for your patience.

    Best Regards,
    Alexis

  • 0 in reply to TI-CSC
    TI__Mastermind 34930 points

    Hello CSC,

    This helps minimize the power consumption of the device. We use these values in our EVM.

    Best Regards,

    Luis Hernandez Salomon