| 摘要 |
PROBLEM TO BE SOLVED: To offer a power failure detector which enables the detection of the open failure of a smoothing capacitor. SOLUTION: A power source is equipped with a DC-DC converter 1 which includes a switching element turned on or turned off by a high frequency and whose output voltage fluctuates at an on-time or off-time of the switching element, and a capacitor C1 which smoothes the output voltage of the DC-DC converter 1. A reference voltage is inputted from a reference voltage generating part 6 for a thermocouple into a microcomputer 10. A power source determination part 14 provided in the microcomputer 10 gets, as a fluctuation width, the difference between the minimum value and the maximum value of the reference voltage outputted from the reference voltage generating part 6 for a thermocouple in a certain determination period, and if the determination period when the fluctuation period is over a specified threshold occurs by the reference number of times continuously, this determination part determines it to be the open failure of the capacitor C1. COPYRIGHT: (C)2005,JPO&NCIPI
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