| 摘要 |
PROBLEM TO BE SOLVED: To prevent leak and falsification of internal data due to erroneous operation of a circuit by giving physical conditions out of normal use conditions such as a high voltage, a low voltage, a high frequency, a low frequency, high temperature, low temperature, etc., which are out of specifications in a semiconductor device. SOLUTION: A physical condition out of a specification detection circuit 120 for detecting that a given physical condition exceeds a scope of specifications determined in advance for an unjust access for inferring internal information by operating the circuit erroneously and observing its output by giving physical conditions out of the specifications is provided. Consequently, it is possible to securely protect the internal information from tamper attack attempting to infer the internal information and prevent falsification and leak of the internal information. In particular, when a PLL (phased locked loop) is used as the detection circuit for detecting the physical conditions out of the scope of specifications, the scope of specifications can be set with high precision, and the detection circuit can be greatly simplified while ensuring high security by the detection of three conditions. |
