Patent ID: 7321138

Claim:
An asymmetrical diac including: a substrate of a first conductivity type with a high doping level, a lightly-doped epitaxial layer of the second conductivity type on the upper surface of the substrate, a heavily-doped first region of the first conductivity type on an upper surface side of the epitaxial layer, a second region of the second conductivity type more heavily doped than the epitaxial layer under the first region of the first conductivity type and that does not extend beyond said first region, a channel stop ring of the second conductivity type more heavily doped than the epitaxial layer, outside of the first region, and a wall of the first conductivity type outside of said ring, joining the substrate; wherein the diac is configured to have a first breakdown voltage for voltages of a first polarity and a second breakdown voltage for voltages of a second, opposite polarity, wherein the first and second breakdown voltages are voltages of different magnitudes.