| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a switching device equipped with a function for detecting disconnection of a lamp load without using a shunt resistor. SOLUTION: This device is composed of a first semiconductor device QA having first (drain) and second (source) main electrodes and a control electrode (gate), a second semiconductor device QB having a first main electrode (drain) respectively connected to the first main electrodes and control gate of the first semiconductor device and a second main electrode (source) connected to a circuit parallel connecting a control electrode (gate), a resistor and a constant current source and a comparing means CMP 1 for comparing a potential difference between the respective second main electrodes (sources) of the first and second semiconductor devices QA and QB. Concerning such a switching device, when the potential of the second main electrode (source) of the first semiconductor device QA exceeds the potential of the second main electrode (source) of the second semiconductor device, the occurrence of disconnection in the lamp load is discriminated.</p> |
