| 摘要 |
PROBLEM TO BE SOLVED: To prevent needless transition from a power saving mode to a normal mode and to extend the life of battery by performing prescribed signal processing that eliminates the repetition of a signal rising part to an external input signal. SOLUTION: A power saving mode maintenance circuit 111 consists of a rectifier diode 113, a capacitor 115 and resistance 117. When voltage is, for instance, >=2 V, a radio wave detection signal that is subjected to waveform shaping by a waveform shaping part 81 is inputted to a 'WAKE-UP signal' detection port of a CPU through the diode 113. The diode 113 is also used not to make a signal to a 'SIGNAL' input port 'dull' by the capacitor 115. In such a case, the 'WAKE-UP signal' is made 'dull' by the action of the capacitor 115. Thus, it is possible to change intermittent waves into almost continuous waves and to make the so-called 'signal rise detection' only the first one time.
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