Ultra-low power energy harvesting electronic devices

Abstract

The electronic device (20; 60; 100; 150; 170; 180; 182; 190; 192; 200; 210) comprises a photovoltaic power unit (21), an energy storage unit (22), a voltage detector (23), a load switch (24), and an application load (25). The electronic device (20; 60; 100; 150; 170; 180; 182; 190; 192; 200; 210) is configured to collect and store energy from ambient lighting and optimize power delivery to the application load (25) from at least one of the collected and stored energy. The photovoltaic power unit (21), the energy storage unit (22), the voltage detector (23), and an input of the load switch (24) are connected to a common point (N1). The photovoltaic power unit (21) collects energy from ambient lighting. An output of the load switch (24) is coupled to the application load. The voltage detector (23) measures the voltage at the common point (N1) to provide an optimized power supply from at least one of the energy storage unit (22) and the photovoltaic unit (21) to the application load, and turns on the load switch (24) when the measured voltage rises to a level equal to or greater than a first voltage. The voltage detector (23) turns off the load switch (24) when the measured voltage falls to a level equal to or less than a second voltage, so that the photovoltaic unit (21) stores energy in the energy storage unit (22). The first voltage is greater than the second voltage.

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