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CELL VOLTAGE VARIATION AT TOP AND BOTTOM CELL WHEN DCC CELL BALANCING USING LTC6811-2

Category: Hardware
Product Number: LTC6811-2
Software Version: 2014.10

Dear,

this board is 2 chip stacking with LTC6811-2 on single PCB. Normally, cell monitoring is ok. However, when is starting cell balancing with DCC mode.top and bottom cell were variation over 10mV.

I would like to receive a review about the circuit diagram. Could you please review below schematic?

  • Hi. I would like to confirm if you used Figure 49 as a reference for your schematic. Kindly confirm. Thank you.

  • Hi mpdumaplin,

    thank you for your reply!

    It makes sense to supply power to ltc6811-2 by connecting as shown below, is it correct?

    best regards,

    daejung

  • The implementation shown in your block diagram is not correct. You cannot connect V- of both the ICs when you are connecting the cells of the pack in series. In your case Cell11+ and Cell12- is shorted together via the orange connection. So Cell12- becomes V- of the top 6811. If you connect V- of both top and bottom 6811 you will be shorting cell12 with cell0. If you wish to keep V- same for both the GND.  

    Although the schematic implementation looks fine to me. 

    Also, in your schematic C12 and C11 cannot be connected via C34 or C41. You need a direct connection from C11 to C12 (short) to enable sum of cells voltage measurement. 

    Regarding your cell balancing issue can you confirm if your S1 input comes from the same C1 input? (before the filters)

    The inductors L3 and L4 are not recommended in our reference design. Can you please clarify why is it installed? 

    C0-1 and C0-2 can be directly shorted to their respective V- connections. 100ohm in path is not necessary