I have developed a project with a MKL03Z32VFG4 with a 32768Hz crystal and powered by a 2045 coin battery.
The application uses only the RTC seconds counter and in normal run mode the clock remains always precise and correct. The mcu enters in VLSS0 easily and current is under 1uA; but when it exits from low power state the clock counter is incorrect and the seconds count can be a lesser or higher, without any apparent reason.
All the prototypes ( >10) we have tested present this problem. Do someone have an idea of where to look, hw? fw?
Thanks for any suggestion...