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BQ34Z100-G1: Average current

Padam Swar
Intellectual 360 points
Part Number: BQ34Z100-G1

Both datasheet and technical reference manual have same less detailed description of average current. 

Qsns

1. Is there another document that has more details on average current?

2. What is the averaging period and number of samples?

I am trying to read more than 1 samples/second and am wondering if Average Current is a way to achieve that. 

  • 0
    TI__Mastermind 25955 points
    Hi Padam,

    The gauge updates current and average current once a second in normal mode and 3 times per minute in sleep mode.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Intellectual 360 points

    Hi Bryan

    Thanks. We understand that the register is updated once per second, but that doesn’t explain what the numbers mean:
    1. Average Current- In normal mode, what is the averaging period?
    2. Current – What does this value represent? Is it averaged over the previous 1 second, or is it an instantaneous value when it updates? Hypothetical example – if the actual current is a repetitive pattern of 500mA out of the battery for 200mS, and 125mA into the battery for 800mS what would the “current” read? Would it read the average (0), or would it read 125, or -500, depending on when the register is updated relative to the pulse?
    3. Current – How precise is the once per second update?
    4. Current – Is there a way to know how old the data is? There seems to be times where the current remains “frozen” for more than 1 second as the actual current (read by DVM) is changing.
    5. Current – Is there a way to read instantaneous current faster than once per second?

    Regards,
    Padam

  • 0 in reply to Padam Swar
    TI__Mastermind 25955 points

    Hi Padam,

    1. In all modes the current is averaged over ~ 1 min. In normal mode the current will be updated once per second. In sleep mode, the current value is updated once per second, but only with a new measurement 3 times per minute.
    2. It is a delta sigma ADC that averages the current over the entire second (1 conversion per second). In the hypothetical example, the value would be between 125 mA and 500 mA, depending on the alignment of the measurements and system current.
    3. The precision is a function of the ENOB, oversampling, current sense resistor size, PPM drift of the current sense resistor, board layout, calibration, etc... The current precision varies with respect to the system and bias.
    4. In normal mode the current will be updated once per second. In sleep mode, the current value is updated once per second, but only with a new measurement 3 times per minute.
    5. No, the gauge updates Current() once per second.

    Sincerely,
    Bryan Kahler