Allen-Bradley Company, LLC

Mamabu Hayakawa

Makoto Shichi

Dennis M Wright

The present invention provides a switching device incorporating a simple circuit capable of avoiding the flash-on of a transistor when a power supply is turned on and off thereby reducing the OFF delay time. The output circuit comprises a FET (145) having a drain and a source connected in series to a current line for supplying a current from a power supply (VD) to an output detector (load) (L), and a photocoupler (149) for applying a driving voltage across the gate and the source of the FET (145) according to the output of an internal circuit (151), a differentiation circuit comprising a capacitor (7) and resistors (5,9) is connected across the drain and the source of the FET (145), and second transistor (3) having a collector and an emitter connected to the gate and the soruce of the FET (145) is driven by a charging current for charging the capacitor (7). When a voltage applied across the drain and the source of the FET (145) starts rising, the second transistor (3) is turned on to turn off the FET (145) forcibly.

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Kariya, Japan

Mamabu Hayakawa