The TPS65987D contains an internal high-voltage LDO which is capable of converting up to 22 V from VBUS to 3.3 V for powering internal device circuitry. The VBUS LDO is only utilized during dead battery operation while the VIN_3V3 supply is not present. The VBUS LDO may be powered from either VBUS1 or VBUS2. The path connecting each VBUS to the internal LDO blocks reverse current, preventing power on one VBUS from leaking to the other. When power is present on both VBUS inputs, the internal LDO draws current from both VBUS pins.