| 摘要 |
PURPOSE:To decrease the number of parts, and to facilitate integration by converting an input signal level into an ignition phase angle. CONSTITUTION:A resistor 12 and a MOS transistor (hereinafter called Tr) 13 for a short circuit are juxtaposed between a P N P N type semiconductor switch such as a gate and a cathode for an SCR 11. A MOS Tr 15 for controlling charging and a capacitor 16 are connected in series between an anode and a cathode for the SCR 11 through a bias circuit 14, and an inverter circuit 17 is connected at the node of the MOS Tr 15 and the capacitor 16. A sensor circuit 19 is connected to a gate for the Tr 15 through an amplifier circuit 18. A time constant circuit is constituted of the Tr 15 and the capacitor 16, and the circuit is controlled by the sensor 19 and the amplifier circuit 18. Consequently, ignition phase can be controlled by the change of an input signal level. A control circuit controlling the SCR 11 is operated from a region having low supply voltage at that time, and the impedance of the Tr 13 is lowered quickly, thus increasing dv/dt resistance.
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