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BQ25120A: bq25120a- I2C is not responsive when sys out disabled

krf
Prodigy 70 points
Part Number: BQ25120A

Hi,

Datasheet specify SYS-out can be disabled over I2C and only can be enabled when MRreset or valid Vin input occur. 

When ı disabled Sys-out, Sys-out really goes down to 0V. In that situation ı want to read battery voltage over I2C but I2C doesn't give response.

Is it due to I2C hardware of bq25120a powered from Sys-out?

And yes ı control bq25120a over I2C succesfully except situation ı mentioned.

So, do you have any opinion to handle that situation?

Thanks...

Best Regards...

  • 0
    TI__Genius 13735 points

    Hi Omer,

    The SYS rail is used to power some of the digital circuitry within the BQ25120A, so the BQ25120A is not able to communicate via I2C when this rail is disabled. SYS disabling is not intended for final applications, and is provided primarily for debugging and development purposes, per the datasheet:

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    Prodigy 70 points

    Thanks for your reply.

    Yes, ı had this information too in early but ı just wanted to check it if there is escape way for it. I think if ı pass all our design concern,  that wouldn't be any problem to using SYS-out disable bit for bq25120a. What do you think about it?

  • +1 in reply to krf
    TI__Genius 13735 points

    Hi Omer,

    In terms of escaping the SYS disable, I believe VIN toggling or WD resetting after 50s will cause you to exit the mode and SYS to recover. Because of the loss of I2C communications we don't recommend the use of this bit.

    Best Regards,

    Juan Ospina