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Transistor base current regulator

  • US 4,684,878 A
  • Filed: 05/08/1986
  • Issued: 08/04/1987
  • Est. Priority Date: 05/08/1986
  • Status: Expired due to Term
First Claim
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1. The combination comprising:

  • first and second power terminals for the application therebetween of an input voltage (VIN);

    an output terminal;

    means for the connection of a load means between said output terminal and said second power terminal;

    a selectively enabled transistor switch having a collector and an emitter defining the ends of its main conduction path and a base for the application thereto of base drive;

    means connecting the collector-to-emitter path of said transistor switch between said first power terminal and said output terminal; and

    controllable base drive means coupled between the base of said transistor switch and said second power terminal for supplying base drive to said transistor switch and causing an amplified current to flow between its collector and emitter, said controllable base drive means including sensing means coupled to the emitter and collector of said transistor switch for sensing when the voltage between the collector and the emitter is less than a predetermined value as a result of excessive base drive and for then reducing the base current flowing in the base of said transistor switch.

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