| 摘要 |
A control circuit and method for using the same in operating a power switch such as a relay, FET, etc., having conductive and nonconductive conditions and adapted to direct a high magnitude driving current from a power supply through an electric load circuit when the power switch is in the conductive condition. Such a power switch can be used to control small motors used extensively in motor vehicles. This control circuit comprises testing means for directing a low magnitude, low duty cycle testing current through the load or motor circuit while the power switch is in the nonconductive condition, sensing means for creating a control signal indicative of a predetermined electrical characteristic, such as current flow, in the load circuit, means for shifting the power switch into the conductive condition for energizing the load when the control signal from the sensing means has a predetermined value, i.e. exceeds a preselected level, and load protecting means for interrupting the high magnitude driving current passing through the load circuit when the driving current exceeds the preselected value. Preferably, the protective means involves no external resetting or time delay in operation.
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