| 摘要 |
It is known that high-power transistors in integrated construction exhibit a number of internal resistors. For example, two base-emitter resistors are provided in a Darlington circuit. In the case of short switching cycles, it is necessary to supply a negative base current -iB to the input of the high-power transistor during turn-off, that is to say to deplete the base. For this purpose, a driver circuit 5 with P- and N-channel 4, 13 is provided, with a positive and negative supply voltage. This driver circuit is driven by a monitoring circuit 2 in such a manner that the P-channel 4 is conducting for turning on the high-power transistor 6 and during operation whilst the N-channel 13 is conducting for turn-off. To avoid heating or power dissipation of the transistor 6 during the turned-off phases due to the negative base current -iB, a detector circuit 15 is provided which senses the switched state of the transistor 6 and interrupts the negative base current -iB a short time after the transistor has been turned off. <IMAGE>
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