| 摘要 |
PURPOSE:To prevent the generation of the trouble and malfunction of a circuit even when high voltage is applied to a drain electrode unexpectedly by mounting an insulated gate type transistor capable of driving a section between a source and a drain so as to be brought to a conductive state only when drain voltage applied between a source electrode and the drain electrode is kept within a predetermined range. CONSTITUTION:When bias voltage VD exceeds the threshold voltage VT2 of a second transistor T2, currents IDS are brought to an interrupted state. It is because the second transistor T2 is conducted and the voltage of a gate for a first transistor is made lower than the threshold voltage VT1 when the bias voltage VD exceeds the threshold voltage VT2. When bias voltage VD lowers, IDS naturally begin to flow again. Consequently, the first transistor T1 in a semiconductor device 1 can be driven so as to be brought to a conductive state only when bias voltage (that is, drain voltage) VD is kept between 0<VD<VT2. Accordingly, even when unexpected quantity, thus protecting a circuit.
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