| 摘要 |
PURPOSE:To turn on or off a gate easily and to form a gate driving circuit simply by connecting the 1st transistor(TR) with two TRs of which polarity is different from the 1st one by Darlington connection. CONSTITUTION:In the figure, Q1 and Q2 show pnp and npn TRs respectively. TRs Q2, Q3 constitute Darlington connection and the emitter of the TR Q3 is used as the cathode K of a gate turn off (GTO) thyristor. Consequently, negative gate bias voltage of the voltage between the gate and cathode of one npn TR is applied between the gate G and cathode K of the GTO thyristor and the input impedance of Darlington connection TR is increased higher than a single TR, so that the outflow of the current is easily performed, a base current component i2 is reduced and large capacity current is turned off easily. Since the current amplification factor of composite TRs at the time of Darlington connection is the product of both TRs Q2, Q3 as compared to the single TR Q2, the gate can be turned off with low gate current and the gate current can be reduced. |
