• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 127 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ27421-G1: Elevated current consumption when addressing other I2C peripherals on the bus

Stephen Snyder
Prodigy 40 points
Part Number: BQ27421-G1

Hello,

I recently found the root cause of elevated current consumption on our device.  The I2C bus that connects our MCU to the BQ27421-G1 is shared with other peripherals.  We had an RTC on it that we were sampling once per second.  The time on the bus for communicating with the RTC is about 3ms.  When the RTC is addressed, the BQ27421-G1 current consumption elevates from 24uA (near the expected SLEEP mode current) to 63uA, and it stays elevated for about 830ms.  Our target system current is about 100uA, so an elevation of 39uA for 80% of the time is very significant.  

Can someone at TI confirm that this behavior is expected based on the chip design?  Additionally, if it is expected, are there any values in data memory that can be adjusted to reduce the time spent consuming excess current after I2C traffic?  This feels like some circuitry that listens for it's I2C address is not timing out fast enough.

Thanks

  • 0
    TI__Expert 8315 points

    Hi,

    Unfortunately, this is just the expected behavior of the device. Whenever there is traffic on the i2c lines, The gauge must turn on oscillators to be able to check what was sent over I2C and this process is expected to take this amount of time. There are no internal parameters on the device that can change this behavior.

    Best Regards,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    Prodigy 40 points

    I'd recommend you consider documenting this in the datasheet.  I2C buses are frequently shared, I expect my use case may be very common, and in this use case the part isn't meeting it's advertised operating specs.