Array of 8 or 12 diodes configured by cells of 2 diodes, each cell being used to protect signal line from transient overvoltages by clamping action. As maximum voltage of each diode is 18 V, maximum input voltage range between two I/Os is either 0 V to 18 V (REF1 = 0 V and REF2 = +18 V) or -9 V to +9 V (REF1 = -9 V and REF2 = +9 V)