Control device for a switching transistor

摘要

A control device for a switching transistor (3) contains a base control circuit (6) having at least one diode (13), the forward direction of which is polarised in the same direction as the base-emitter path of the switching transistor. Between the control input (7) of the base control circuit (6) and the collector of the switching transistor, a saturation control circuit (8) having at least one diode is located, the forward direction of which corresponds to the collector-emitter path of the switching transistor. To avoid high turn-on losses and ensure a high turn-off speed of the switching transistor, the saturation control circuit (8) is provided with at least a second diode (9) connected in series with the first one in the same direction and is designed in such a manner that the base-emitter voltage of the switching transistor is higher than the collector-emitter voltage approximately by the forward voltage drop of a diode (9; 10) when a turn-on control voltage is applied to the control input. <IMAGE>