Abstract: A power supply circuit comprising: a load; a resistor coupled the load; a first secondary battery; a second secondary battery; a switch configured to switch between a first state in which the first secondary battery and the second secondary battery are charged and a second state in which load current is supplied from the first secondary battery and the second secondary battery to the load based on current flowing through the resistor; and a shunt regulator configured to control the switch.

Abstract: A surge protection circuit includes a first terminal that is coupled to a transmission path, a second terminal that is coupled to a PHY circuit to transfer a signal on a physical layer, a clamping unit that is coupled so as to branch from a first line between the first terminal and the second terminal, the clamping unit clamping a voltage applied to the first terminal to a specific clamping voltage, and a first semiconductor switch that is arranged between the second terminal and a branching point at which the clamping unit branches from the first line, the first semiconductor switch having a rectification direction away from the second terminal toward the first terminal, the first semiconductor switch having a higher reverse breakdown voltage than a clamping voltage of the clamping unit.

Abstract: A surge protection circuit includes a first terminal that is coupled to a transmission path, a second terminal that is coupled to a PHY circuit to transfer a signal on a physical layer, a clamping unit that is coupled so as to branch from a first line between the first terminal and the second terminal, the clamping unit clamping a voltage applied to the first terminal to a specific clamping voltage, and a first semiconductor switch that is arranged between the second terminal and a branching point at which the clamping unit branches from the first line, the first semiconductor switch having a rectification direction away from the second terminal toward the first terminal, the first semiconductor switch having a higher reverse breakdown voltage than a clamping voltage of the clamping unit.

Abstract: A connector includes a first terminal to which a power supply is connected, the power supply being a direct current power supply, a second terminal to which a signal ground of the direct current power supply is connected, and a third terminal connected to a frame ground, the third terminal being arranged at a location between the first terminal and the second terminal.

Abstract: A power supply circuit comprising: a load; a resistor coupled the load; a first secondary battery; a second secondary battery; a switch configured to switch between a first state in which the first secondary battery and the second secondary battery are charged and a second state in which load current is supplied from the first secondary battery and the second secondary battery to the load based on current flowing through the resistor; and a shunt regulator configured to control the switch.