| 摘要 |
PURPOSE:To protect an FET surely even when a momentary DC high voltage is developed by providing a resistance, MOSFET and bipolar transistor between the input and earth terminals of the MOSFET that is to be prevented from breakdown. CONSTITUTION:The P-N-P bipolar transistor 8 is provided between the input terminal T and earth terminal E of the first MOSFET2, which is to be prevented from breakdown, in parallel. Similarly a series circuit that consists of the resistance 9 and the second MOSFET10 is connected to said elements in parallel, and the base of the transistor 8 is connected to the gate of the transistor 10 through the connection point of both the resistance 9 and the element 10. In this way, even when high voltage is applied to the terminal T, current flows through the transistor 8, and the high voltage is not applied to the gate of the element 2. At this time, the transistor 8 conducts according to a time constant of both the capacitance 10a of the element 10 and the resistance 9, and the applied high voltage is discharged to the terminal E. |
