SLVAET3 October 2021 TPS8802
It is most efficient to connect the MCU directly to the battery if the MCU can withstand the full battery voltage range. Connect MCUSEL to GND to set the MCU LDO to 1.8 V during the power-up sequence. The battery voltage overrides VMCU without drawing significant current. When the system is powered up, disable the MCU LDO to save power. Ensure the battery voltage does not exceed 3.5 V when connected to VMCU.