Protection device of programmable semiconductor surge suppressor having deep-well structure

A protection device of programmable semiconductor surge suppressor having deep-well structure is provided comprising one, two or four protection units, each of which is composed of a PN-junction diode, a PNPN-type thyristor and a NPN-type triode connected with each other. It is characterized in that in the diode area on the frontal side of the N-type semiconductor base is formed a PN junction with impurity concentration changed gradiently from top to bottom according to the order of P+, P, N and N+; and a group of deep-wells with P-type impurities are positioned at the interface of the PN junction, making the PN junction form a concave-convex type interface. The present invention can be used in the program-controlled switchboard to protect the Subscriber Line Interface Circuit (SLIC) board. The above improvement can further improve the anti-lightning and anti-surge performance and the energy discharge capability of the whole device. The device of the present invention can reach a level of 3000˜3500 V according to the anti-lightning performance test.