BQ27426: I2C channel status when no battery is connected

Ignacio Majcherczyk

Part Number: BQ27426
Other Parts Discussed in Thread: BQ25638

Tool/software:

DEar all

I'm designing a system with the BQ27426 battery fuel gauge and a BQ25638 battery charger IC

and my question is what the status of the I2C bus is when no battery (and also no VBUS in the case of the BQ25638) is present

I need to know this because the system may be powered with other sources aside from VBUS or battery, and this chips are connected to an I2C bus with more

peripherals attached.

My question here is if there will no contention of the powered off chips with the active I2C bus

regards

Ignacio

over 1 year ago

0 Diego over 1 year ago

TI__Mastermind 29970 points

Hi Ignacio,

If the BAT pin is not powered with at least 1.9V the device will not be able to communicate i2c.

Regards,

Diego

0 Ignacio Majcherczyk over 1 year ago in reply to Diego

Prodigy 170 points

Hello Diego

that's okay, but my question is what happens with the I2C bus to which the BQ27426 is attached when the BQ27426 is not powered. Will the I2C lines get stuck low, disabling all other peripherals? or the I2C bus will be unaffected?

Ignacio

0 Diego over 1 year ago in reply to Ignacio Majcherczyk

TI__Mastermind 29970 points

Hi Ignacio,

If the device is not powered this will not cause the i2c lines to get held low and will not affect communication with other devices on the same i2c lines.

Regards,

Diego

0 Ignacio Majcherczyk over 1 year ago in reply to Diego

Prodigy 170 points

Okay, and for the case of the BQ25638, what happens if it is not powered? Will it behave the same with the I2C bus?

Ignacio

0 Adrian over 1 year ago in reply to Ignacio Majcherczyk

TI__Mastermind 37981 points

We can not answer question for a charger IC, you will have to post a new question for the charger group to answer that question.

Regards,

Adrian

Power management

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BQ27426: I2C channel status when no battery is connected