POWER SUPPLY CIRCUIT

A power supply circuit includes: a primary capacitor configured to temporarily store the energy from an energy harvester; a storage element configured to store the energy for supply to a load; a buck converter configured to charge the storage element with the energy stored in the primary capacitor; a secondary capacitor configured to connect to the primary capacitor to operate in a first state where the voltage between both terminals of the primary capacitor is applied to both terminals of the secondary capacitor and a second state where the voltage between both terminals of the primary capacitor is not applied to both terminals of the secondary capacitor; and a control circuit configured to operate with the secondary capacitor as a power source.