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BQ34110EVM-796: Current sensing wrong polarity?

Christopher H
Prodigy 50 points
Part Number: BQ34110EVM-796
Other Parts Discussed in Thread: BQ34110, BQSTUDIO

Hello,

After replacing the BQ34110 chip on an EVM and going through the firmware programming (bq34110_v0_02_build_9.srec) and calibration process, I noticed that the current sensing polarity seems to be wrong. In other words, when I enable the battery charger, the BQ34110 [DSG] flag is set and the gauge indicates a negative current in bqStudio 1.3.54.1. Similarly to charging, discharging incorrectly causes the [CHG] flag to set. When I apply a 2 A load for calibration, specifying -2000 mA applied current results in the gauge adjusting at around +2000 mA. I tried initiating the GPC Cycle, but I am unable to get [FC] to set in this state. I have attached a copy of the gauge's data memory. Please let me know how I can correct this problem.

bq34110.gg.csv.zip

Thank you,

Christopher

  • 0
    TI__Mastermind 25955 points
    Hi Christopher,

    Thank you for including the gg.csv file.

    Please also attach a marked up schematic from the EVM User Manual indicating what jumpers are shorted and where the battery/supply/load are connected on the schematic.

    Thanks!

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 50 points

    Hi Bryan,

    Here is the marked up schematic. I removed the VEN related jumpers for clarity, but I had the same result with the out of the box configuration diagrammed in the EVM user manual.

    Thank you,

    Christopher

  • 0 in reply to Christopher H
    Prodigy 50 points

    Just to totally rule out the BQ34110 rework, I replaced the chip yet again and attempted calibration using the factory firmware. To my surprise, it now works as intended. Other than firmware programming, the only other difference is having accidentally entered in +2000 mA applied current instead of -2000 mA during the initial calibration on the previous chip. Could that have somehow caused the sign to be permanently inverted?

    Thank you,

    Christopher

  • 0 in reply to Christopher H
    TI__Mastermind 25955 points
    Hi Christopher,

    Thank you for including the schematic and swapping out the device. I'm glad to hear the device is now operational - inverted current reading caused by flipping the signs on applied current during calibration is definitely plausible. To determine root cause, you could try flipping it once more to see if the issue returns.

    Sincerely,
    Bryan Kahler