| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor switch which prevents damages when a load is short-circuited. SOLUTION: An output MOSFET is turned on by an electromotive force of a photovoltaic element and a load is connected to a power supply, and an overcurrent sensor detects a load overcurrent to generate an overcurrent signal. A latch circuit receives an overcurrent signal to output a shutdown signal to a shunt MOSFET to be energized. The shunt MOSFET is in series connected to a current limiting resistance between both ends of the photovoltaic element, to form the shunt for deviating a current derived from the optical electromotive force element from the output MOSFET, and when the output MOSFET is energized, the output MOSFET is non-energized to cut off the load. The shunt MOSFET and the current limiting resistance are separately formed from the latch circuit, and the current limiting resistance is connected to between a control electrode of the output MOSFET and a positive pole of the photovoltaic element, and when the shunt MOSFET is energized, a current derived from the photovoltaic element is limited and the photovoltaic element applies a supply voltage to the latch circuit, so that the latch circuit holds the shutdown signal. |
