| CPC H02J 7/00712 (2020.01) [G05F 1/56 (2013.01); H01M 10/0525 (2013.01); H01M 10/4264 (2013.01); H01M 10/44 (2013.01); H01M 10/48 (2013.01); H01M 50/109 (2021.01); H02J 7/0048 (2020.01); H02J 7/0063 (2013.01); H02J 7/007 (2013.01); H02J 7/345 (2013.01); H02J 50/001 (2020.01); H02J 50/20 (2016.02); H02J 50/80 (2016.02); H01M 2220/30 (2013.01); H02J 2207/20 (2020.01)] | 20 Claims |

|
1. A wireless device, comprising:
an energy harvester configured to convert energy harvested from radio-frequency (RF) signals 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 associated with the wireless device; and
a power management circuit coupled to the energy harvester, the first and second ports, and the load, the power management circuit including:
a controller configured to select one of the energy harvester, the external USB power source, or the battery as a selected power source at system startup based on one or more of an amount of the harvested voltage, a presence of a connection with the external USB power source, a presence of a connection with the battery, or an amount of charge or voltage stored by the battery; and
a switcher matrix configured to power the load at system startup using the selected power source.
|