Photo-coupler apparatus

A photo-coupler apparatus comprising:

• a light emitting element for emitting light by an input signal;
• a photoelectromotive diode array for generating photoelectromotive force by receiving an optical signal from said light emitting element;
• a light sensitive impedance element series-connected to said photoelectromotive diode array, said light sensitive impedance element changing its impedance value according to the intensity of said optical signal from said light emitting element, wherein said light sensitive impedance element comes into a small impedance state when said optical signal from said light emitting element is strong and it comes into a large impedance state when said optical signal from said light emitting element is weak;
• a zener diode parallel-connected with said light sensitive impedance element;
• at least one output MOSFET whose gate and source are connected to respective ends of the series-connected circuit comprised of said photoelectromotive diode array and said light sensitive impedance element;
• and
• a normally-ON drive transistor whose control electrode is connected to the node of said photoelectromotive diode array and said light sensitive impedance element, and whose one pair of conducting electrodes are connected to the gate and the source of said output MOSFET respectively.

A photo-coupler apparatus comprising:

• a light emitting element for emitting light by an input signal;
• a photoelectromotive diode array for generating photoelectromotive force by receiving an optical signal from said light emitting element;
• a light sensitive impedance element series-connected to said photoelectromotive diode array, said light sensitive impedance element changing its impedance value according to the intensity of said optical signal from said light emitting element;
• a normal diode array parallel-connected with said light sensitive impedance element;
• at least one output MOSFET whose gate and source are connected to respective ends of the series-connected circuit comprised of said photoelectromotive diode array and said light sensitive impedance element;
• and
• a normally-ON drive transistor whose control electrode is connected to the node of said photoelectromotive diode array and said light sensitive impedance element, and whose one pair of conducting electrodes are connected to the gate and the source of said output MOSFET respectively.