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BQ40Z50-R2: Please review the schematic

Chase Jeong
Mastermind 7505 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQSTUDIO

Dear TI experts,

My customer started their new project with BQ40Z50-R2. Could you review the schematic and layout?

4S1P(5400mAh)_V01_240202.pdf

4S1P_V1.0 PCB.pdf

4S1P_V1.0_GB.zip

Best regards,

Chase

  • +1
    TI__Mastermind 26255 points

    Hi Chase,

    Are you aware that some of the capacitors on the 40z50EVM are DNP? (SRN/SRP pins)

    A second GND plane is needed on your schematic, reference the EVM schematic.

    TS3/4 appear to have resistors not a thermistors. 

    The resistor on the PTC pin should be a PTC thermistor.

    I recommend reviewing the EVM schematic and layout guidelines in the datasheet.

    EVM schematic found here - bq40z50EVM Li-Ion Battery Pack Manager Evaluation Module (Rev. C) 

    datasheet for layout guidelines - BQ40Z50-R2 1-Series, 2-Series, 3-Series, and 4-Series Li-Ion Battery Pack Manager datasheet (Rev. C) (ti.com)

    Regards,

    Evan

  • 0 in reply to Diego
    Mastermind 7505 points

    Dear Evan,

    Thank you for your support, and hope you had a good day.

    Are you aware that some of the capacitors on the 40z50EVM are DNP? (SRN/SRP pins)

    --> I will not insert 2 capacitors. (C5 and C6)

    A second GND plane is needed on your schematic, reference the EVM schematic.

    --> Customer's PCB have only 2 layers. Is it okay? or should we add more layers to make second GND plane?

    TS3/4 appear to have resistors not a thermistors.

    --> I will directly connect TS3 and TS4 to GND. (Customer will use only 2 thermistors.)

    The resistor on the PTC pin should be a PTC thermistor.

    --> I will change to NTC thermistor.

    Please check the question above. Thanks.

    Best regards,

    Chase

  • +1 in reply to Chase Jeong
    TI__Mastermind 26255 points

    Hi Chase,

    Your customer will need a second gnd plane, on the EVM schematic linked above, there are 2 GNDs referenced, "GND" and "CHGGND", the gauge needs a separate GND plane from the rest of the components.

    Remember to disable the thermistor pins in BQstudio.

    the thermistor needs to be a PTC type.

    Thanks,

    Evan

  • 0 in reply to Diego
    Mastermind 7505 points

    Dear Evan,

    I discussed about 2nd GND plane with my customer. They said that they have to setup with 2 layers because of BOM cost.

    - What would be happen if we don't have CHGGND? (i.e. accuracy of gauge will be decreased, or something else..)

    - Or, Is it okay to make CHGGND in either TOP or BOT layer separately?

    Please check this issue. Thanks.

    Best regards,

    Chase

  • +1 in reply to Chase Jeong
    TI__Mastermind 26255 points

    Hi Chase,

    We recommend having 2 planes; however I have seen this done by isolating the 2 GNDs. I would reference the EVM layout and schematic.

    Regards,

    Evan