Patent attributes
M pieces of n-well regions nW are provided on a main surface of a p-type silicon substrate 3, and p-well regions pW are provided among the n-well regions adjacent to one another. Moreover, each of the M pieces of n-well regions nW includes an n-type diffusion region nD and a p-type diffusion region pD1, which are formed therein. Furthermore, the p-well region pW includes a p-type diffusion region pD2 therein. The n-type diffusion region nD in a j-th of the n-well region nW is connected to the p-type diffusion region pD1 in a (j+1)-th of the n-well region 10. The p-type diffusion region pD1 in the first n-well region nW is connected to a first terminal 1. The n-type diffusion region nD in the M-th of the n-well region nW is connected to a second terminal 2. In response to a potential relation between desired terminal to be protected (not depicted) and discharge terminal (not depicted) during a normal operation, the first terminal is connected to either one of the terminals, of which potential is higher, and the second terminal 2 is connected to the other of which potential is lower.
