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.

BQ25790: Ship Mode with no I2C Host

Part Number: BQ25790

We are hoping to utilize the BQ25790 ship mode functionality. The datasheet specifies the I2C is still enabled so the controller can be woken up by changing the SDRV_CTRL[1:0] register bit back to 00 to turn on the external ship FET. There is also the QON pin that can be pulled low to manually change the SDRV_CTRL[1:0] register bit back to 00 without any software requirements. This is what we intend to use. In our power scheme, once the BQ25790 enters ship mode our MCU is shut down and the I2C connection is lost, so our only option is to exit through the QON pin.

My question is, is it ok our I2C connection will be lost, and can we still exit ship mode through the QON pin? I want to ensure when the I2C connection is lost we are not put into shutdown mode as we do not want to rely on an external adapter plug-in to wake up the IC again.

I am also curious if the only option to enter ship mode is changing the SDRV_CTRL[1:0] register bit to 10 through I2C. Is there any way to use the QON or another pin on the IC to enter this mode with a button? We are hoping to offer a power on & off button along with a software power down.

Thanks

  • Hi Logan,

    Yes, /QON lets you exit ship mode even if I2C is not available.

    Unfortunately, /QON only offers a way for hard reset, i.e. momentary power down and back up.  There is no other pin that can allow you to enter ship mode.

    Regards,

    Jeff

  • Hello Jeff,

    Thank you for the response that did address all of my questions but I now have a follow-up question.

    What happens if QON is pulled low while the device is in Idle mode and the external ship FET is on (SDRV_CTRL[1:0] register bit is 00)? This is also assuming its not held for 10 seconds to trigger a system power reset. Would this do nothing and be "ignored" by the IC?

    Thanks

  • Hi Logan,

    I haven't tested that on this device but on our previous devices with /QON, that is the case.

    Regards,

    Jeff