Patent ID: 6580184
Filing Date: 2003-06-17
Classification: H01L

Abstract:
A protection unit for a semiconductor integrated circuit connected to a first terminal, the protection unit comprising:a low impurity region formed in a semiconductor substrate of a first conductivity type, the low impurity region having a second conductivity type; a first high impurity region of the first conductivity type formed in the low impurity region and connected to the first terminal; a second high impurity region of the second conductivity type formed in the low impurity region and connected to the first terminal; a third high impurity region of the second conductivity type formed in the semiconductor substrate and connected to a second terminal; a fourth high impurity region of the first conductivity type formed in the semiconductor substrate and connected to the second terminal; a fifth high impurity region of the second conductivity type formed in the low impurity region; and a switch circuit connected between the fifth high impurity region and the second terminal, the switch circuit providing a current path when a voltage at the first terminal exceeds a threshold voltage of the switch circuit.