Patent ID: 9712165
Date: 2017-07-18
CPC Classifications: H03K

Claim:
1. A semiconductor device comprising: a first power source pad configured to be supplied with a first power source voltage; a first power source line configured to be connected to said first power source pad; a first ground line; an output circuit configured to be operated using said first power source voltage; a second power source pad configured to be supplied with a second power source voltage; a second power source line configured to be connected to said second power source pad; a second ground line; a signal line configured to be connected to an output end of said output circuit; an input circuit configured to be connected to said signal line at an input end to receive a signal from said output end, and be operated using said second power source voltage; a main protection circuit unit configured to provide a main discharge route between said first power source pad and said first ground line, between said first ground line and said second ground line, and between said second ground line and said second power source pad; and a sub protection circuit unit, wherein said output circuit includes: wherein said sub protection circuit unit includes: wherein when an electrostatic discharge (ESD) surge is applied at one of the power source pads, when the first PMOS transistor is turned on, at least one additional discharge route is formed from the first power source pad through the first power source line, the signal line, and the first PMOS transistor to the second ground line to reduce the first stress voltage to a second stress voltage applied between the source and the gate of the transistor of the input circuit and prevent a breakdown of the transistor of the input circuit, and in a normal operation, a voltage value of the first power source voltage is lower than a voltage value of the second power source voltage and the potential of the back gate of the first PMOS transistor is higher than the potential of the source of the first PMOS transistor.