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BQ25125: I2C interface unresponsive

Lidong Yu
Intellectual 1756 points
Part Number: BQ25125

I am using the BQ25125 battery charge IC and attempting to communicate with it over I2C.  It appears as though it nacks all I2C requests when the input power is not connected unless I pull the CDn  pin high.  However, with CDn pulled high it doesn't charge the battery when input power is connected.

I would like to always be able to communicate with it over I2C and always have it charge the battery when input power is present.  Is it possible to pinstrap the CDn pin with a resistor and still be able to always communicate with the part and always have it charge the battery then input power is present?  Or do I need to constantly monitor the state of the input power and toggle the CDn pin accordingly?  Thanks.

  • 0
    TI__Genius 12475 points

    Hi Lidong,

    /CD pin toggles between Active bat(I2C available) or HiZ mode (I2C off). 

    When the input power is connected, you don't need to pull /CD high to communicate. You can use the /PG pin to determine if the /CD pin will need to be pulled up before communicating to the device. Typically you can use a adapter present flag to determine the power cable state. You will need to drive the /CD pin through an IO if you do need to communicate to the device on battery only mode. 

    Let us know if you have any questions. 

    Regards,

    Gautham