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BQ76942: I2C communication without REG1 enabled

Andreas Hogberg
Prodigy 20 points
Part Number: BQ76942

Hello TI team,

I'm about to use: BQ76942, Communications Interface: I2C, REG1 LDO default: disabled.

Not intend to use internal LDO, REG1 and REG2. Run BQ76942 in fully autonomous mode, no external MCU.
REGIN and BREG connected to VSS.
REG1: floating
REG2: floating.

Calibration and OTP programming will be done by using external equipment. Pull-up for I2C will be on placed in
external equipment. Attach simplified block diagram.
Cells will be assembly after calibration and OTP programming. 

Question 1: Is it possible to communicate BQ76942 according to attached block diagram? Guess REG18 is used for internal logic.

Question 2: Once calibration and OTP programming is done, pull-up on SDA and SCL is left floating, is that okay?
Question 2.1: If floating is not okay, how should SDA and SCL be handled since I can't have pull-up to REG1?

Regards,

Andreas

  • +1
    TI__Mastermind 40680 points

    Hello Andreas,

    It is perfectly okay to use an external regulator for the pull-ups, you do not need to use REG1/REG2 with our I2C. 

    Andreas Hogberg said:
    Question 1: Is it possible to communicate BQ76942 according to attached block diagram? Guess REG18 is used for internal logic.

    Yes, this looks okay to me Slight smile. 3.3-V pull-up should be more than okay. Pull-up resistors may be better to be slightly larger, we use 10-kOhm pull-ups in our EVM.

    Andreas Hogberg said:
    Question 2: Once calibration and OTP programming is done, pull-up on SDA and SCL is left floating, is that okay?

    Yes, that is okay if you are not interfacing with a MCU. Keep in mind that during OTP, the BAT and VC10 voltages need to be ~11-V or so.

    Andreas Hogberg said:
    Question 2.1: If floating is not okay, how should SDA and SCL be handled since I can't have pull-up to REG1?

    See answer above. These can be left floating.

    Let me know if there are any additional questions!

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 20 points

    Hello Luis, thank you for fast response. Very much appreciated!

    Have a nice day!

    BR,
    Andreas