Integrated semiconductor device providing for preventing the action of parasitic transistors

Abstract

An electric motor drive system is disclosed which includes a required number of motor driver circuits connected one to each motor armature coil. Fabricated in the form of an integrated circuit, each such motor driver circuit has a parasitic transistor unavoidably created between two neighboring transistors. The parasitic transistor would become conductive when the driver circuit output had a negative potential, adversely affecting the driver circuit operation. An additional transistor is provided in one embodiment of the invention in order to inhibit such action of the parasitic transistor. Becoming conductive when the driver circuit output goes negative, the additional transistor prevents conduction through the parasitic transistor. Another parasitic transistor is intentionally created in another embodiment for the same purpose.