DYNAMICALLY SELECTABLE POWER CONFIGURATIONS

A wireless device includes an energy harvester to convert harvested energy into a harvested voltage, a first port selectively connected to an external USB power source, a second port selectively connected to a battery, a load including a plurality of circuits, and a power management circuit coupled to the energy harvester, the first and second ports, and the load. The power management circuit includes a controller configured to select one of the energy harvester, the USB power source, or the battery as a power source at system startup based on one or more of an amount of the harvested voltage, a presence of a connection with the USB power source, a presence of a connection with the battery, or an amount of charge or voltage stored by the battery. The power management circuit also includes a switcher matrix to power the load at system startup using the selected power source.