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Semiconductor device

  • US 6,483,365 B2
  • Filed: 03/19/2002
  • Issued: 11/19/2002
  • Est. Priority Date: 08/02/2000
  • Status: Active Grant
First Claim
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1. A semiconductor device comprising:

  • a signal terminal;

    a high potential side power supply terminal;

    a low potential side power supply terminal;

    a first wiring connected to said high potential side power supply terminal;

    a second wiring connected to said low potential side power supply terminal;

    an internal circuit to which power is supplied from said first and said second wirings;

    first and second resistance elements whose each one end is connected to a first node, said first node being at a wiring connecting said signal terminal with said internal circuit;

    a first protection element having a first terminal connected to said first wiring and a second terminal connected to the other end of said first resistance element, voltage-current characteristics of said first protection element when said second terminal is grounded having a negative resistance region and a holding region;

    a second protection element having a third terminal connected to the other end of said second resistance element and a fourth terminal connected to said second wiring, voltage-current characteristics of said second protection element when said fourth terminal is grounded having a negative resistance region and a holding region;

    a third protection element having a fifth terminal connected to said first wiring and a sixth terminal connected to said second wiring, said third protection element being made up of a MOS transistor, and voltage-current characteristics of said third protection element when said sixth terminal is grounded having a negative resistance region and a holding region;

    a fourth protection element made up of a diode whose anode is connected to a second node and whose cathode is connected to said first wiring, said second node being at said wiring connecting said signal terminal with said internal circuit, and the relations of “

    Vh2(I1)+r2×

    I1

    Vf4+Vr3>

    Vr2” and



    Id2>

    I1

    being satisfied, where I1 represents a value of a first current flowing from said signal terminal to said low potential side power supply terminal via said second resistance element, said second protection element and said second wiring, Id2 represents a value of said first current when it causes destruction of said second protection element, r2 represents a resistance value of said second resistance element, Vf4 represents a voltage when a current starts to flow through said fourth protection element in case that a positive voltage is applied to said anode of said fourth protection element while grounding said cathode of said fourth protection element, Vh2(I1) represents a voltage drop of said second protection element caused by said first current, Vr2 represents a negative resistance starting voltage in said negative resistance region of said second protection element, and Vr3 represents a negative resistance starting voltage in said negative resistance region of said third protection element; and

    a fifth protection element made up of a diode whose cathode is connected to said second node and whose anode is connected to said second wiring.

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