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Current sensing circuit formed in narrow area and having sensing electrode on major surface of semiconductor substrate

  • US 5,828,308 A
  • Filed: 08/05/1997
  • Issued: 10/27/1998
  • Est. Priority Date: 08/06/1996
  • Status: Expired due to Term
First Claim
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1. A current sensing circuit for monitoring a current driving transistor connected at a first current node thereof to a load to see whether or not the amount of driving current is within a standard range, comprising:

  • a current-to-voltage converter connected between a power voltage line and a second current node of said current driving transistor for producing a potential level variable with the amount of said driving current at said second current node, said current-to-voltage converter and said current driving transistor being implemented by a vertical transistor fabricated on a semiconductor substrate structure having a major surface, said vertical transistor includinga drain region of a first conductivity type formed on said semiconductor substrate and providing said second current node and a sensing node on a first area exposed to said major surface,a base region of a second conductivity type opposite to said first conductivity type and formed over a second area of said drain region,a source region of said first conductivity type formed in a central area of said base region and having an area serving as said first current node and exposed to said major surface,a channel region formed between said drain region and said base region for providing a current path between said drain region and said source region,a gate insulating layer covering a part of said channel region and a peripheral area of said base region, anda gate electrode formed on said gate insulating layer;

    a reference potential source for producing a constant reference potential level; and

    a voltage comparator having two input nodes connected to said sense node and said reference potential source so as to compare said potential level with said reference potential level for producing a signal representative of said driving current out of said standard range.

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