Part Number: BQ25120
VIN=0, MR is floating in my test case, and BQ25120 appears to be entering ship mode once VBatt drops to below 3.2V (with 1uA current as expected in our design). However, the battery voltage slowly recovers and once it hits 3.23V, I am seeing strange current transients. It seems the BQ25120 is exiting ship mode when VBatt > 3.23V and then re-entering it immediately when VBatt once again goes below 3.2V. Current changes constantly in the range of 1uA to 120uA. It looks like the BQ is powering up sys and unregulated briefly and waking our MCU, then entering ship mode again?
This is the behavior I would expect if MR is pulled low, but I am leaving this pin floating and it has internal pull-up. The documentation is not clear on what state is entered when VBatt < BUVLO. It only mentions "lockout" but it's unclear what state that is.
Questions:
1. What am I missing here?
2. What state is entered when VBatt < BUVLO, and under what conditions is that state existed?
Note that this is a BQ25120 not BQ25120A.
Cheers
Philip