| 摘要 |
PURPOSE:To attain the protection of a transistor (TR) over a wide range and to integrate a driving circuit and a protection circuit by setting optionally a Zener voltage of a Zener diode and a voltage of a gate-off power supply to take the size of the TR and the circuit characteristic into consideration. CONSTITUTION:When an ON-signal is inputted to an R8, a base current of a T4 is interrupted and an ON-base current flows in the path of Egon R3 T2 TRS to turn on the TRS. In this case, the base current T1 is cut off and a current flows in the path of Egdet R1 D1 TRS Egoff. When the collector current of the TRS is an excess current in this state, the base current of the TRS becomes relatively deficient, the collector voltage is increased, and when the relation of (Zener voltage of a Zener diode ZD1 + voltage drop ph.c of an input diode D3) < (collector voltage drop of TRS+Egnff) is obtained, the D1 is turned off and an off-base current flows in the path of Egoff TRS T3 D5 R5 to protect the TRS by turning instantly off the TRS. |
