Patent ID: 7889778

Claim:
A protection circuit, comprising: a signal generator operable to develop a security signal on an output node; a conductive path having an input node coupled to the output node of the signal generator and having an output node, the security signal applied on the input node being provided on the output node of the conductive path after a delay time; a comparison circuit coupled to the respective output nodes of the signal generator and the conductive path and operable to compare the signals on these output nodes only after a comparison time that is greater than the delay time, the comparison circuit being further operable to develop a comparison signal responsive to the comparison; and a trigger clock generator operable to develop a trigger clock signal having a period that is equal to or greater than the comparison time, and wherein the signal generator is operable to develop the security signal responsive to the trigger clock signal and wherein the comparison circuit is operable responsive to the trigger clock signal to compare the signals on the output nodes of the signal generator and the conductive path wherein the trigger clock signal generator includes a second conductive path that substantially determines the period of the trigger clock signal.