POWER SUPPLY CIRCUIT

A power supply circuit supplies power from a first battery to a first load. The first load includes a capacitor that needs to be charged before activation. The power supply circuit includes: a main circuit that supplies power from the first battery to the first load; and a backup circuit having a precharge circuit for charging the capacitor and that supplies power from the first battery to the first load. When charging the capacitor, power is supplied from the first battery to the first load by using the backup circuit. After charging of the capacitor is completed, power is supplied from the first battery to the first load by using the main circuit.