Power supply system

An endoscope system comprising:

• an endoscope including an imaging unit that images an object, and a cable;
• a housing apparatus detachably connected to the endoscope via the cable;
• a plurality of power source units that are provided in the housing apparatus and configured to output electric power different from one another;
• a plurality of switches, each provided in an output stage of each of the power source units of the housing apparatus and formed of a back-to-back connection in which same terminals of the two FETs are connected;
• a common power supply line that makes electric power output through the switches in common in the housing apparatus, and supplies the common output to the endoscope from the housing apparatus;
• a determination unit that is provided in the endoscope, and determines whether or not the electric power supplied through the common power supply line is appropriate electric power to operate the endoscope;
• a communication line through which the endoscope requests the housing apparatus to output appropriate electric power, when the determination unit determines that the electric power supplied through the common power supply line is not appropriate electric power to operate the endoscope;
• and
• a controller that is provided in the housing apparatus, selects a power source unit from the power source units in accordance with a request for appropriate electric power input through the communication line, and controls the switches to output electric power generated by the selected power source unit to the endoscope.