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BQ76930: Schematic review for 8 cells

Kum Hoo Lee
Expert 1855 points
Part Number: BQ76930

Dear Sir/Madam,

Need help to review my schematic for 8 cells connection. Please help and advise. Want to ensure the connection from VC0 to VC10 is correct. Thank you very much. Hope to hear from you soon!8cell connection.pptx

  • 0
    TI__Guru 54715 points
    Hi Kum Hoo,
    The use of the cells is correct, but there are some refinements needed for the component connections:
    The bottom of C8 should connect to GND1 instead of VC0, see the data sheet figure 8-2 for reference.
    The related power connections should also be considered as connections are needed (BAT, VC5X). They need filter resistors and capacitors.
    VC5B and VC5 must be separate. The R12, R11 connection is appropriate for VC5B.
    The bottom of C4 should connect to VC5X
    VC5 must connect to the cell with its own resistor.
    The top of C5 connects to VC5
    VC5B should have its own capacitor to VC5X
    Add the diodes from VC5 to VC5X and VC10 to BAT shown in the data sheet, conventional diodes.
  • 0 in reply to WM5295
    Expert 1855 points

    Dear Sir,

    Need your help for the schematic review once again. Please find the attached file for schematic that I key in. Hope to hear from you.

    Thanks and best regards,

    KHschematic check.pptx

  • 0 in reply to Kum Hoo Lee
    TI__Guru 54715 points
    Hi KH,
    The 4th cell will be the connection to the bq76930 group boundary since each group will support 4 cells. The 4th cell, CN1 pin 5 should connect to support the bq76930 pins VC5, VC5X and VC5B. There may be several ways to do this, this method may help:
    D4 should connect to VC5 rather than VC5B.
    The left side of R48 and R49 should connect to cell4 at CN1 pin 5.
    The top of C5 must connect to VC5 rather than VC5B.
    The top of C9 must connect to VC5X rather than VC5.
    The bottom of C4 must connect to VC6 rather than VC5B.
    The bottom of C3 must connect to VC6 rather than VC5X .
    At the bottom cell connection filtering should be done to VSS (GND1) rather than differentially, see the data sheet figure 8-2:
    The bottom of C8 must connect to GND1.
    An additional capacitor must be used to connect between VC0 and GND1.
  • 0 in reply to WM5295
    Expert 1855 points

    Hi Sir,

    Can I ask for your help to check on my schematic connection? Do advise if there is any wrong connection on the 8 cells design. Thank you very much!

    8 cell connection - Project.pdf

  • 0 in reply to Kum Hoo Lee
    TI__Guru 54715 points
    Hi Kum Hoo,
    The connection for 8 cells looks correct. For the power supply: another 1k resistor is needed from point "A" (CN1 pin 5) to VC5X. Also D3 anode (node at top of D3 with R37 and R38 connection) is cell 8 (CN1 pin 1).