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BQ76930: about the BQ76930 read CC and change to current

Part Number: BQ76930

Dear TI expert,

in SLUSBK2H file in page 23, CC is coulomb counter, The unit of coulomb is 1A * 1S,My understanding of ALWAYS ON and 1-SHOT is as follows

In ALWAYS ON mode, Read once every 250ms, and then accumulate the values

in 1-SHOT mode, i can get one CC value, which is current*250ms, is right?

in this file the CC unit is uV, not coulomb, if i want to get the current value, Can I read the value of CC in 1-shot mode and divide it by the resistance of the shunt,that is i=CC/shut_resistance

  • Hello,

    Currently, all our employees will be out of office from 11/24 - 11/27 for Thanksgiving break.  Everyone will be back in office Monday, 11/28, and your question will be answered then.  Apologies for any inconvenience!

    Best,

    Andria

  • Hello,

    In response to each of your questions:

    What are ALWAYS ON and 1-SHOT?

    • ALWAYS ON: This will integrate the current (in other words, average the current) every 250-ms, continuously.
    • 1-SHOT: Whenever the host MCU wants, it can ask the BQ76930 to take a single measurement.  This measurement will still integrate over 250 ms; however, as the name 1-SHOT implies, this measurement is only done once.

    Please note that ALWAYS ON and 1 SHOT use the same measurement method, but ALWAYS ON takes the integrated measurements every 250 ms, whereas 1-SHOT takes the integrated measurement whenever the MCU asks the device to take it.

    How do I get the current value?

    • Divide the CC voltage by the sense resistor value, or: Current = CC value × CC LSB value / sense resistor.  Be sure to convert units where needed.  Remember that the CC is an integrating converter, and the calculation will give an ‘average’ current.

    More information can be found in sections 5.4 and 5.5 of the FAQ document: bq76920, bq76930, bq76940 AFE FAQ (Rev. A) (ti.com).

    I hope this helps!

    Best,

    Andria