| 摘要 |
A load condition determining apparatus having a drive circuit having first and second MOS-transistors, the drains of the MOS-transistors are connected to a power supply respectively, the control-gate thereof are connected to a voltage stepping circuit, and the source of the first MOS-transistor is connected both to a load circuit and to one input terminal of a differential amplifier while the source of the second MOS-transistor is connected both to a load equivalence circuit having resistors and a capacitor and to the other input terminal of the amplifier. The resistance of the load equivalence circuit is equalized with the resultant resistance component of the load circuit while the time constant of the capacitance and part of the resistance of the load equivalence circuit is modeled after the rush current of the load circuit, when operated, in the apparatus according to the invention. The normal and abnormal conditions of the load circuit can be determined by the occurrence of the balance and the unbalance between input voltages to the differential amplifier from the sources of the MOS-transistors in accordance with the normal condition, the short-circuited condition, or the disconnected condition of the load circuit. In order to distinguish the abnormal conditions from a provisional change in the load circuit, the upper and lower threshhold voltage levels are provided in a comparing circuit. |
