Patent ID: 7110226

Claim:
A regulator protection circuit comprising: an abnormality detection circuit that receives an abnormality detection voltage whose level varies according to an operation state of a regulator, that, once the abnormality detection voltage turns from lower than a first threshold level to higher than the first threshold voltage, keeps outputting an abnormality-indicating signal until the abnormality detection voltage becomes lower than a second threshold level that is equal to or lower than the first threshold level, and that, once the abnormality detection voltage turns from higher than the second threshold level to lower than the second threshold voltage, keeps outputting a normality-indicating signal until the abnormality detection voltage becomes higher than the first threshold level; an abnormality detection incidence checking circuit that checks, based on an output of the abnormality detection circuit, whether or not the abnormality-indicating and normality-indicating signals have alternated a predetermined number of times within a predetermined length of time; and an abnormality detection level setting circuit that, when the abnormality detection incidence checking circuit recognizes that the abnormality-indicating and normality-indicating signals have alternated the predetermined number of times within the predetermined length of time, decreases at least the second threshold level out of the first and second threshold levels.