Aspects of the present disclosure are directed to circuits, apparatuses, and methods for power management. According to an example embodiment, an apparatus includes a low drop-out (LDO) voltage-regulation circuit configured to generate a regulated voltage from a voltage provided to a supply terminal of the LDO voltage-regulation circuit. The apparatus also includes switching circuitry coupled to the LDO voltage-regulation circuit and to a plurality of voltage sources. The voltage sources include at least power line carried along with a data bus and another voltage source. Each of the plurality of voltage sources provides a respectively different voltage range. The switching circuitry is configured, in response to a power-related condition of the plurality of voltage sources and while maintaining power to the LDO voltage-regulation circuit, to select and couple one of the voltage sources to the supply terminal and uncouple other ones of voltage sources from the supply terminal.