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CCS/BQ40Z60: Does FG go back to unsealed mode from sealed mode?

Emma Wang_DELL EMC
Intellectual 695 points
Part Number: BQ40Z60

Tool/software: Code Composer Studio

Hi Batt:

    1,I have one question about unsealed mode. I noticed that there is one description that FG can't return to unsealed mode from sealed mode like below. But I also saw that document gives method of changing to unsealed mode. So I have some confusion.

2, Regarding cell balancing, how FG achieve cell balancing in relax mode without current passed through cell? Why do cell balancing in relax mode? and what advantages?

3,in SLUA450, on page6, why is DOD[i] calculated by below formula?  Because I think the unit of left side doesn't match with one of right side.

DOD[i]=DODstart + dDOD*I.

Thanks in advance!

Emma 

  • 0
    TI__Mastermind 42535 points

    Hi Emma,

    1. Once in sealed mode, the gauge will always return back to sealed mode if a reset command or POR is done. The only way to permanently unseal the device is to put it in full access mode using the keys and then reprogram the fw.

    2. Cell balancing current in relaxation bypasses the cells by using the internal FET at the cell input that shorts it for the duty cycle time to GND. We generally do not advise cell balancing in relax. It is useful in cases of extremely unbalanced cells.

    3. dDODxI refers to delta DOD at the current, not exactly the multiplication. So, the units are the same. DOD is calculated under load therefore the load current is required here.