Patent ID: 8610216

Claim:
A protection cell of an integrated circuit against electrostatic discharges, electrically connected to a pad and to first and second power supply rails of the circuit, the protection cell comprising: a diode having an electrode connected to a region of a first conductivity type and electrically connected to the second power supply rail and having an electrode electrically connected to a region of a second conductivity type and electrically connected to the pad, and in parallel with the diode, a thyristor having an electrode electrically connected to a region of the first conductivity type and electrically connected to the pad and having a gate electrically connected to a region of the second conductivity type and electrically connected to the first rail, the first and second conductivity types being such that, in normal operation, when the circuit is powered, the diode is non-conductive, said cell comprising first to fifth regions of alternated conductivity types having, in top view, the shape of concentric rings of increasing respective diameters, wherein: the first to third regions are formed in a central well of the first conductivity type; the first region is of the second conductivity type; the fourth and fifth regions are formed in a peripheral well of the second conductivity type; and the first and fourth regions are electrically connected to said pad, the second and third regions are electrically connected to the second power supply rail, and the fifth region is electrically connected to the first power supply rail.