| 摘要 |
PROBLEM TO BE SOLVED: To obtain a watchdog timer circuit which does not malfunction due to a noise to which an ignition signal or the like is mixed. SOLUTION: The watchdog timer circuit for detecting the rise or fall of a clock signal, charging/discharging a capacitor C1, and, when the voltage of the capacitor C1 exceeds a prescribed range, generating an alarm signal is provided with an integration means for integrating a noise whose pulse width is sufficiently smaller than that of the clock signal and removing the noise from the clock signal, and is constituted so as to detect the rise/fall of a clock signal outputted from the integration means and charge/discharge the capacitor C1. Thereby malfunctions such as failure of generation of a necessary alarm signal due to a noise can be prevented.
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