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BQ28Z610-R1: Questions about the BQ28Z610-R1

Eduardo Barcellos
Intellectual 420 points
Part Number: BQ28Z610-R1
Other Parts Discussed in Thread: BQ25883, EV2400

Hello,

I'm having some issues with the BQ28Z610-R1, and to help solve it I got a few questions. For reference, this is my circuit, using the BQ25883 as charger and the BQ28Z610-R1 as gauge:

Questions:

1) If I remove the batteries and the USB cable that provide power to the BQ25883 charger IC, completely powering down the board, and then plug only the batteries back on, I'm unable to reach the BQ28Z610-R1 via I2C, even through the EV2400/Battery Management Studio. If I then plug the USB cable to the board, providing power to the BQ25883 which will then send voltage to the BQ28Z610-R1's PACK pin, the BQ28Z610-R1 will then start responding to I2C and to Battery Management Studio, and will continue to work even if I then unplug the USB cable, leaving only the batteries. Shouldn't the BQ28Z610-R1 always use power from the batteries through the VC2 pin regardless of the PACK input? Is there any configuration setting I'm missing for this?

EDIT: I tried disabling SLEEP in Settings / DA Configuration, but it didn't help.

EDIT: Maybe it's Voltage Based Shutdown? I sent the SHUTDOWN command twice to trigger it and it had this exact effect. As I can understand from the datasheet, for Voltage Based Shutdown to be triggered the cell voltage has to be under the shutdown voltage for the shutdown time. This shutdown time would then prevent voltage shutdown from triggering by just removing the batteries. But I'm not sure if I understood it correctly.

2) Before the USB cable was plugged on case 1 above, I checked and pin 9 (CHG) of the BQ28Z610-R1 had ~4V and pin 7 (DSG) had 0V. After plugging the USB cable, they both had ~17.2V in a constant voltage (no oscillations). Is this value (17.2V) correct? Does the BQ28Z610-R1 have a voltage booster to generate this voltage from the ~7.9V of the batteries? I looked at the datasheet and it does state that the output voltage range at CHG and DSG is 26V maximum, but I'd like to confirm this.

Thanks for your help,

Ed

PS: This is my BQ28Z610-R1 settings:

  • 0
    Intellectual 420 points

    Continuing: I thought this issue could be a result of a bad solder at the BAT (VC2) pin, but the BAT pin voltage being reported when the system is working with only the batteries (no USB cable) is this:

    Therefore, I assume this part is ok.

    Also, the PACK pin voltage is 8.051V, which is greater than the BAT voltage. I assume its just a result of the 17.2V at the DSG pin.

    For more details, this is the entire Registers screen when the system has only the batteries (no USB cable) and nothing using the batteries (nothing discharging):

  • 0 in reply to Eduardo Barcellos
    Intellectual 420 points

    After looking for the solution, I believe it's not a problem at all. This chip will indeed enter shutdown mode if disconnected from both the battery and the power supply, requiring then a voltage at the PACK pin to return. Can anyone confirm this?

  • 0 in reply to Eduardo Barcellos
    TI__Guru** 105590 points

    Hello Eduardo,

    That is correct operation. If the gauge is powered down or goes into shutdown mode you must supply voltage on the PACK pin to wake the gauge up, otherwise it will be unresponsive like you have seen.

    Sincerely,

    Wyatt Keller