Hello,
According to the Connectivity Framework Reference Manual (inside KW38 docs folder > docs > wireless > common), TMR_StartLowPowerTimer starts a low-power timer which can operate across all power modes, including low-leakage modes. This timer is necessary because MCU can enter low-power mode if there are only active low-power timers.
Taking a look at TimersManager.h, valid range for gTmrApplicationTimers_c macro should be user defined depending on the timers needed by the application.
Regards,
Eduardo.