SLUUBT5C November 2018 – June 2021 BQ40Z80
PRES is sampled four times per second, and if PRES is high for 4 samples (one second), the OperationStatus[PRES] flag is cleared. If PRES is low for 4 samples (one second), the OperationStatus [PRES] flag is set, indicating the system is present (the battery is inserted).
If the [NR] bit is set, the PRES input is not monitored. If [NR] is set and [EMSHUT_EN] is cleared, the PRES pin should be tied to VSS. If [NR] and [EMSHUT_EN] are set, then the PRES input must be configured correctly for that function.