| 摘要 |
PROBLEM TO BE SOLVED: To provide a security circuit that can perform simultaneous trimmings on a plurality of samples. SOLUTION: The security circuit contains a frequency detecting circuit (11) which is used for detecting the frequency abnormality of a clock signal and a system resetting circuit (13) used for forming a system resetting signal based on the detected result of the frequency detecting circuit (11). The security circuit also contains a self-trimming circuit (14) which changes the trimming value of the target set value of the frequency abnormality detection in a state that a clock signal having the frequency which is equal to the target set value of the frequency abnormality detection at the frequency detecting circuit is supplied to the frequency detecting circuit, and, decides the trimming value of the target set value of the frequency abnormality detection based on the detected result of the frequency detecting circuit whenever the trimming value is changed. Since the trimming procedures among a plurality of samples can be made equal to one another in the course of self-trimming, this security circuit can perform simultaneous trimmings on the plurality of un-diced samples. COPYRIGHT: (C)2006,JPO&NCIPI
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