| 摘要 |
PURPOSE: To provide a signal transmission circuit for an IGBT gate drive circuit which can be shortened in OFF time and, accordingly, can be improved in noise resistance. CONSTITUTION: In a signal transmission circuit for an IGBT gate drive circuit constituted by connecting an open collector type TTL, a transistor, etc., to the primary side of a photocoupler PC and providing a CR circuit to the input circuit of the photocoupler PC as a countermeasure against noise, the resistor between the signal transmission lines of the CR circuit is divided into resistors R21 and R22 and a diode D1 is connected between the dividing point of the resistors R21 and R22 and the terminal of a capacitor C1 . The diode D. becomes the by-pass circuit of a resistor R3 connected to one signal transmission line, a Zener diode ZD1 , and one R21 of the divided resistors when the capacitor C1 discharges. Therefore, the OFF time of the signal transmission circuit is shortened and the noise resistance of the circuit is improved, because the discharge from the capacitor C1 is accelerated. |
