| 摘要 |
PURPOSE:To avoid a malfunction by connecting a discharge preventing diode in series to a switch circuit. CONSTITUTION:A sudden drop of the power supply voltage even when caused during an OFF period is prevented by a diode 8. Thus the electric charge of capacitors 21-2n are not discharged toward the power supply. Therefore, these capacitors are discharged by a circuit consisting of a resistance 31, a Zener diode 61 and a resistance 71, for example. In this case, no operation is carried out to change the electric charge of the gate input capacity of MOSFETs 12-1n. As a result, the voltage of the gate input capacity of FETs 12-1n is kept lower then the cutoff voltage level despite a sudden drop of the power supply voltage. Thus a switch circuit never has a malfunction. |
