Determination device and switch system equipped therewith

A determination device used for a semiconductor switch including a junction field-effect transistor having a gate and a source corresponding to the gate, the device comprising:

• a resistor that has a first end and a second end, the first end being connected to the gate;
• and
• a determination circuit that determines that an overcurrent is flowing through the semiconductor switch when there is a predetermined change in a gate-source voltage of the junction field-effect transistor in a range smaller than a gate drive voltage given between the second end of the resistor and the source, wherein
• the semiconductor switch is a dual-gate type junction field-effect transistor having two gates and two sources,
• the two gates include a first gate and a second gate,
• the two sources include a first source corresponding to the first gate and a second source corresponding to the second gate,
• the determination device includes two resistors, and includes two determination circuits,
• the two resistors include a first resistor connected to the first gate, and a second resistor connected to the second gate,
• the two determination circuits include a first determination circuit corresponding to the first gate and the first source, and a second determination circuit corresponding to the second gate and the second source, and
• the determination device further includes a third determination circuit that determines whether or not there is an anomaly of the semiconductor switch based on a determination result of the first determination circuit and a determination result of the second determination circuit.