| 摘要 |
PURPOSE:To prevent the erroneous conduction of a transistor upon turning a power supply on and ensure the small and less expensive design of a converter by using pertinently a difference in timing between the d.c. power supply of a control circuit and voltage between the drain and source of a transistor at the time of turning on the power supply. CONSTITUTION:When voltage is applied between the drain and source of a transistor 7 upon turning a power supply on, the output voltage V0 of a d.c. power supply 15 is in the neighborhood of 0V. The transistor 7, therefore, is not energized and kept shut off properly. After voltage between the drain and source of the transistor 7 is raised and stable, the output voltage V0 of the d.c. power supply 15 rises and reaches power supply voltage VCC. Thereafter, clamping voltage due to a diode 20 becomes equal to or above the power supply voltage VCC of the d.c. power supply 15 and, therefore, even if the gate of the transistor 7 is actuated, the diode 20 does not have any adverse effect upon the driving operation of the gate. According to the aforesaid construction, the erroneous conduction of the transistor 7 can be prevented and a large and high cost relay 4 can be eliminated, thereby enabling the reduction of size and cost of a converter device. |
