SLUSDV2A May 2020 – May 2021 BQ25798
BQ25798 backup mode has been optimized for use with a single input source, populating ACFET1-RBFET1 as described in Section 126.96.36.199.
It is possible to use the backup power supply mode in conjuntion with the dual-input mux. Either ACIN1 or ACIN2 can transition into backup mode without dropping PMID when backup mode is enabled and the currently active source is removed. However, when BQ25798 transitions from backup mode to ACIN2, PMID will drop to GND for a brief period of time. Only ACIN1 supports transitioning back from backup mode without dropping PMID.
The following sequence is used to transition the source which powers the PMID load from the battery to the ACIN2 source while optionally re-arming the backup mode: