Power supply device

A power supply device comprising:

• a switch that is disposed in a power supply path leading from a main power source to a load, and is configured to bring into conduction and interrupt the power supply path;
• a downstream sensing means for sensing a power supply state of a load-side power supply path, which is a power supply path between the switch and the load;
• a comparing means for comparing a downstream voltage, which is a voltage of the load-side power supply path, with a predetermined threshold voltage;
• and
• a control unit to which outputs of the downstream sensing means and the comparing means are input,
• wherein the control unit includes:
• a switch control means for turning the switch on/off;
• a conduction determination means for determining whether the switch is in an ON or OFF state based on the output of the downstream sensing means;
• and
• an overcurrent sensing means for causing the switch control means to turn the switch off, upon sensing that the downstream voltage is lower than the threshold voltage.