Patent ID: 6404016
Filing Date: 2002-06-11
Classification: G06F

Abstract:
A semiconductor device comprising:a first circuitry; a second circuitry; a first power source including a first low potential side power source line and a first high potential side power source line for supplying a first power source voltage to said first circuitry; a second power source including a second low potential side power source line and a second high potential side power source line for supplying a second power source voltage to said second circuitry; a signal line connected between said first circuitry and second circuitry for transferring a signal between said first circuitry and said second circuitry; a MOS transistor with a gate connected to said signal line, and a source or drain connected to said second low potential side power source line or said second high potential side power source line, said MOS transistor serving as an input circuit of the second circuitry; and a protection circuit disposed serially between said first low potential side power source line and said second low potential side power source line, said protection circuit comprising a first directional element which becomes conductive when a potential of said first low potential side power source line is larger than that of said second low potential side power source line by a prescribed value, and a second directional element which becomes conductive when a potential of said second low potential side power source line is larger than that of said first low potential side power source line by a prescribed value, said first directional element and said second directional element are serially connected in reverse direction with no branching point therebetween.