To reduce power consumption of an information processor without lowering a processing speed for all kinds of processings.
A control microcomputer 101 sends a voltage setting value Vo that is slightly lower than a normal operation voltage of a CPU 103 to a DC/DC converter 102, converts a voltage from an internal battery to a value requested by the microcomputer 101 and applies it to the CPU 103. Subsequently, a self-test command is sent from the microcomputer 101 to the CPU 103. In response to it, the CPU 103 performs operation check, sends a test result to the microcomputer 101 and determines whether or not a received test result is acceptable. When the test result is acceptable, a similar operation is performed about a voltage value Vn that is slightly lower than the preceding voltage V(n-1) and operation check is repeatedly performed, further lowering the voltage gradually. When the test result is not acceptable, the voltage V(n-1) is detected as a minimum operation voltage and the operation is finished.
MASUNO TAKASHI
ASANO MICHIHIRO
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