SLVSE46A November 2017 – January 2018 TPS65680
Internal power for the logic core and analog reference system is primarily sourced from the VIN pin but can be also sourced from VGH after the IC has powered up. When V(VIN) rises above the under-voltage lockout threshold, the reference system and internal LDO are powered up, allowing the IC to boot and enter STANDBY mode. Once powered up, an internal power-path is enabled, sourcing power for the reference system and INT_LDO from either VIN or VGH, allowing the IC to remain functional for as long as either supply is available. Note that the order in which VIN and VGH are supplied to the IC is irrelevant but the IC does not power up without VIN being present. In particular, the IC does not power up if VGH is supplied but VIN is below the UVLO threshold.