Patent ID: 6426665
Filing Date: 2002-07-30
Classification: H01L,H03F

Abstract:
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; a first protection element having a first terminal connected to said first wiring And a second terminal connected to a first node, voltage-current characteristics of said first protection element when said second terminal is grounded having a negative resistance region and a holding region, and said first node being at a wiring connecting said signal terminal with said internal circuit; a second protection element having a third terminal connected to said first node 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 closer to said signal terminal than said first node; 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; and a resistance element connected to said first node and said second node therebetween, the relations of â€œVh2(I1)+r3Ã—I1&gE;Vf4+Vr3>Vr2â€  and â€œId2>I1â€  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 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, r3 represents a resistance value of said resistance element, Vf4 represents a voltage when a current starts to flow through said fourth protection element when 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.