POWER SOURCE APPARATUS AND A SYSTEM

A power source apparatus includes a plurality of first power sources, each connected to a load through a power supply line, and at least one second power source, which is a sub power source to be used when the first power source is unable to output a predetermined voltage. The second power source is connected in parallel to the power supply line of at least one of the first power source through a diode. The second power source is provided on an anode side of the diode, the load is configured to operate at a voltage equal to or more than a first voltage, the first power source outputs a second voltage higher than the first voltage, the second power source outputs a third voltage, which is higher than the first voltage, the voltage output through the diode from the second power source being lower than the second voltage.