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BQ40Z60: Using without external temperature sensors; the Cell temperature = -273 deg C

Joshua Kim
Intellectual 590 points
Part Number: BQ40Z60
Other Parts Discussed in Thread: BQSTUDIO

Hi, I made a new board whose circuit came from the bq40z60evm except for the external temperature sensors which I eliminate, and connect nothing to the pins.

I disabled the unused temperature sensors by clearing the corresponding flag in the bqStudio; Settings>Temperature Enable [TS4=0][TS3=0][TS2=0][TS1=0][TSInt=1].

However, setting the Temperature mode is obscure. The reference manual says the flag 1 means reporting the FET temperature, and 0 means reporting the cell temperature. So I configure this way because the non-existent external sensors cannot report the FET temperature;  Settings>Temperature Mode [TS4=0][TS3=0] [TS2=0][TS1=0][TSint=1]

As a result, the temperature report is as follows: the int temperature = FET temperature = 23.5 deg C, while the Cell temperature = -273 deg C. Is it correct function? 

Thanks,

J.H.Kim

  • 0
    TI__Mastermind 42535 points
    Your thread's been assigned to me. Please expect a reply in 48 hours.
  • 0 in reply to Batt
    Intellectual 590 points

    I've got following results according to the Data Memory > Setting > Configuration > Temperature Enable and Temperature Mode variations.

    I think that no.5 or 6 is the best decent choice. But it doesn't satisfy both the cell temperature and FET temperature simultaneously.

    What is the best choice among these eligibles?  Of course, there are no external sensors on the board.

    NO Temperature Enable   Temperature Mode   Temperature (degC)
    TS4 TS3 TS2 TS1 TSInt   TS4Mode TS3Mode TS2Mode TS1Mode TSIntMode   Cell FET
    1 0 0 0 0 0   0 0 0 0 0   -273 -273
    2 0 0 0 0 0   0 0 0 0 1   -273 -273
    3 0 0 0 0 0   1 1 1 1 0   -273 -273
    4 0 0 0 0 0   1 1 1 1 1   -273 -273
    5 0 0 0 0 1   0 0 0 0 0   26 -273
    6 0 0 0 0 1   0 0 0 0 1   -273 26
    7 0 0 0 0 1   1 1 1 1 0   26 -273
    8 0 0 0 0 1   1 1 1 1 1   -273 26
    9 1 1 1 1 0   0 0 0 0 0   -53 -273
    10 1 1 1 1 0   0 0 0 0 1   -53 -273
    11 1 1 1 1 0   1 1 1 1 0   -273 -53
    12 1 1 1 1 0   1 1 1 1 1   -273 -53
    13 1 1 1 1 1   0 0 0 0 0   26 -273
    14 1 1 1 1 1   0 0 0 0 1   -53 26
    15 1 1 1 1 1   1 1 1 1 0   26 -53
    16 1 1 1 1 1   1 1 1 1 1   -273 26
  • 0 in reply to Joshua Kim
    TI__Mastermind 42535 points

    If you don't have any ext sensors please set Temperature Enable TSInt to 1. TS Mode doesn't matter. The thermistor should be in proximity to your cell or fet for the appropriate bit to be chosen. In this case, since you're having only 1 TS, please set TS Mode to 0 for TSInt. You need cell temp for impedance track measurements.

  • 0 in reply to Batt
    Intellectual 590 points
    Thanks for the precious advice. Your recommendation is the no.5 in my summary conditions above. However, the cell temperature and FET temperature looks not to be satisfied simultaneously; cell temp = 26, but FET temp = -273. In this condition, can the weird FET temp cause a problem?

    Thanks,
    J.H.Kim
  • 0 in reply to Joshua Kim
    TI__Mastermind 42535 points
    No cell temperatures are what matter for the impedance track calculations and protections. FET temp is usually just for information.
  • 0 in reply to Batt
    Intellectual 590 points
    Thanks a lot! Your answer clarifies my question.

    Thanks again,
    J.H.Kim