US Patent 9368486 Direct connected silicon controlled rectifier (SCR) having internal trigger

In one aspect, a direct connected silicon control rectifier (DCSCR) includes a substrate having a semiconductor surface, a parasitic PNP bipolar transistor and a parasitic NPN bipolar transistor formed in the semiconductor surface. The parasitic PNP bipolar transistor includes a p+ emitter, an nbase and a pcollector and the parasitic NPN bipolar includes an n+ emitter, a pbase and an ncollector. The DCSCR also includes an electrically conductive line connecting an n+ contact to the nbase to a p+ contact to the pbase so that the nbase and the pbase are shorted.