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BQ27421-G1: Reset by BIN

Kazuki Itoh
Genius 10770 points
Part Number: BQ27421-G1

Hi team,

My customer experienced I2C communication error, so looking for the method to reset BQ27421-G1 externally from MCU.

1. Is his understanding correct?

BQ27421 basically has two ways to reset. Removing the battery and connect it again, and inputting High to BIN.

2. Can BIN port be controlled by MCU externally?

Regards,

Itoh

  • 0
    TI__Mastermind 24870 points

    Hello Itoh-san,

    1. The way to reset the bq27421 is either through a power on reset or sending the "reset" command.

    2. BIN port is the battery insertion detection scheme. It should be tied to ground with a 10kOhm resistor or the thermistor pin on the battery pack.

  • 0 in reply to Kang Kang
    TI__Genius 10770 points

    Hi Kang Kang-san,

    Thank you for your response.

    (1) My customer observes I2C hangs up. Is it possible that the state is in SHUTDOWN mode?

    (2) If shutdown mode, it may return by toggling GPOUT. Could you please let me know the right timing of the toggling specifically?

    (3) My customer observes the gauge does not output I2C ACK. Battery voltage can be confirmed from the SRX pin. VDD = 0V, so 1.8V VDD is not working. Battery thermistor pin is connected to TS.

    (4) The customer observed the reset operation with asserting BIN = HIGH. Is it right use case of BQ27421?

    Regards,

    Itoh

  • 0 in reply to Kazuki Itoh
    TI__Mastermind 24870 points

    Hello Itoh-san,

    1. I2C hangs up with I2C SCL low or I2C SDA low? If both low, it may be in shutdown, can you measure the LDO output on VDD pin? If it is in shutdown, this pin should be at 0 V.

    2. Yes, just toggle it high for a few milliseconds. I believe the best way would be to toggle, confirm communications is okay, then untoggle.

    3. Yes, this confirms the device is in shutdown, see (1) above.

    4. No, reset the gauge via I2C command or power on reset the chip. You will see that INITCOMP is clear.