| 摘要 |
PURPOSE:To obtain a PNPN switch excellent in noise resistance having a steep rise, by inserting a capacitor between a base of an NPN transistor (TR) and ground. CONSTITUTION:A capacitor C0 is inserted between the base of an NPN TRQ2 and ground in a PNPN switch circuit consisting of a PNP TRQ1, a Zener diode D1, the NPN TRQ2 and an NPN Darlington TRQ3. Thus, a transient current flowing to a resistor R2 is reduced through capacitance division to prevent the NPN TRQ2 from turning on. In applying a capacitor to the collector of the NPN TRQ2, the PNPN switch circuit has excellent noise resistance against noise with steep rise. The capacitor can easily be realized by a BC diode. |
