LEISTUNGSENDSTUFE MIT EINER DARLINGTON-SCHALTUNG ZUM SCHALTEN EINER INDUKTIVEN LAST, INSBESONDERE DER ZUENDSPULE EINER BRENNKRAFTMASCHINE

摘要

The proposal is for a power output stage with a Darlington circuit (11, 12) for switching an inductive load, especially the ignition coil of an internal combustion engine. In order to predetermine the mode of operation of the power stage, there is a switch (24) bypassing the base-emitter path of the Darlington circuit (11, 12) which is closed when the output stage is switched off and opened when the output stage is switched off with limited voltage. The output of a voltage divider consisting of at least two resistors (16, 18) and bypassing the switching path of the Darlington circuit (11, 12) is connected to the junction between the switch (24) and the base of the Darlington circuit (11, 12), whereby the switch (24) is connected in parallel to a part (18) of the voltage divider. With the switch (24) open, the Darlington circuit is again controlled via the resistor (16) when a low limit voltage of e.g. 35 V is reached, so that, in the event of the drive of an ignition coil, spark-free switch-off is obtained. Only very few simple and cheap components are needed herefor.